US6243288B1 - Giant magnetoresistive sensor, thin-film read/write head and magnetic recording apparatus using the sensor - Google Patents

Giant magnetoresistive sensor, thin-film read/write head and magnetic recording apparatus using the sensor Download PDF

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US6243288B1
US6243288B1 US09/642,003 US64200300A US6243288B1 US 6243288 B1 US6243288 B1 US 6243288B1 US 64200300 A US64200300 A US 64200300A US 6243288 B1 US6243288 B1 US 6243288B1
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film
magnetic
ferromagnetic
composite
films
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Chiaki Ishikawa
Kaori Totsuka
Yoshio Suzuki
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HGST Japan Ltd
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Hitachi Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/09—Magnetoresistive devices
    • G01R33/093—Magnetoresistive devices using multilayer structures, e.g. giant magnetoresistance sensors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/33—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
    • G11B5/39—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
    • G11B5/3903—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects using magnetic thin film layers or their effects, the films being part of integrated structures
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/33—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
    • G11B5/39—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
    • G11B5/3903—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects using magnetic thin film layers or their effects, the films being part of integrated structures
    • G11B5/3967—Composite structural arrangements of transducers, e.g. inductive write and magnetoresistive read
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/33—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
    • G11B5/39—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
    • G11B2005/3996—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
    • G11B5/09—Digital recording
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/33—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
    • G11B5/39—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
    • G11B5/3903—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects using magnetic thin film layers or their effects, the films being part of integrated structures
    • G11B5/3906—Details related to the use of magnetic thin film layers or to their effects
    • G11B5/3945—Heads comprising more than one sensitive element
    • G11B5/3948—Heads comprising more than one sensitive element the sensitive elements being active read-out elements
    • G11B5/3951—Heads comprising more than one sensitive element the sensitive elements being active read-out elements the active elements being arranged on several parallel planes
    • G11B5/3954—Heads comprising more than one sensitive element the sensitive elements being active read-out elements the active elements being arranged on several parallel planes the active elements transducing on a single track
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/40—Protective measures on heads, e.g. against excessive temperature 

Definitions

  • the present invention relates to a magnetic head to record and reproduce information on and from a magnetic recording medium, and more particularly to an improved giant magnetoresistive sensor and a magnetic recording/reproducing apparatus equipped with said sensor.
  • GMR giant magnetoresistance
  • a conventional giant magnetoresistive sensor is shown in FIG. 7 . It consists of a substrate 5 and several layers sequentially formed thereon. Adjacent to the substrate are a magnetic shield layer 10 and a magnetic gap layer 20 . On the magnetic gap layer 20 is a magnetoresistive film 30 , which consists of a ferromagnetic film (free layer) 35 , a copper layer 40 , a ferromagnetic film (pinned layer) 65 , and an antiferromagnetic film 70 , which are formed sequentially one over another.
  • the arrow 55 indicates the direction of magnetization. With the magnetoresistive film 30 patterned, there are arranged an electrode film 90 and a permanent magnet layer 80 at each side thereof.
  • the top is covered with a magnetic gap layer 100 and a magnetic shield layer 110 .
  • the magnetoresistive film mentioned above is characterized in that the pinned layer has its magnetization pinned in the direction of element height (depth) by the exchange bias magnetic field from the antiferromagnetic layer.
  • the free layer has the axis of easy magnetization parallel to the cross-track direction (z direction) of the head.
  • the magnetization in the entire free layer be kept parallel to the cross-track direction of the head so that the free layer does not suffer magnetic saturation when a signal magnetic field from the medium is applied upward and downward in the direction of the element height of the head.
  • the magnetization in the free layer does not become uniformly parallel to the cross-track direction of the head because the free layer receives a static magnetic field which occurs as the pinned layer (orienting vertically to the medium surface) becomes magnetized.
  • the head becomes sensitive unequally to the positive and negative magnetic fields and reproduces a large peak asymmetry of read-back waveform. This not only adversely affects the improvement of error rate by signal processing such as PRML (partial response sampling plus maximum likelihood detection) but also lowers the output.
  • PRML partial response sampling plus maximum likelihood detection
  • V + denotes the peak value of the positive output
  • V ⁇ denotes the peak value of the negative output
  • FIG. 8 There is disclosed in Japanese Patent Laid-open No. 169026/1995 a giant magnetoresistive sensor designed to reduce the peak asymmetry of read-back waveform. As shown in FIG. 8, it has a magnetoresistive film 30 consisting of a ferromagnetic film (free layer) 35 , a copper layer 40 , a composite ferromagnetic film (pinned layer) 50 , and an antiferromagnetic film 70 .
  • the pinned layer 50 which is a composite ferromagnetic film, consists of two ferromagnetic films 51 and 53 (of Co or the like) and a non-magnetic layer 52 (or Ru or the like), the former having their magnetization strongly coupled in the antiparallel direction through the latter.
  • the two ferromagnetic films produce magnetic moments aligning in the antiparallel direction, thereby canceling out each other. The result is a reduction of static magnetic field applied to the free layer from the pinned layer.
  • the second ferromagnetic film 53 of the pinned layer 50 has its magnetization pinned by the antiferromagnetic film 70 .
  • FIG. 9 There is disclosed in Japanese Patent Laid-open No. 7235/1996 another giant magnetoresistive sensor designed to reduce the peak asymmetry of read-back waveform. As shown in FIG. 9, it has a magnetoresistive film 30 consisting of a ferromagnetic film (free layer) 35 , a copper layer 40 , and a composite ferromagnetic film (pinned layer) 50 .
  • the pinned layer 50 which is a composite ferromagnetic film, consists of two ferromagnetic films 51 and 53 (of Co or the like) and a non-magnetic layer 52 (or Ru or the like), the former having their magnetization strongly coupled in the antiparallel direction through the latter, like the aforesaid head.
  • the two ferromagnetic films 51 and 53 should have an adequate thickness, so that the pinned layer has a large effective coercive force for it to be of self-pinned type.
  • the result is a reduction of static magnetic field applied from the pinned layer and obviation of the antiferromagnetic film to fix the pinned layer.
  • the advantage is a reduction of the entire film thickness of the head and a reduction of the gap length.
  • FIG. 10 it has a magnetoresistive film 30 consisting of a first antiferromagnetic layer 70 , a first pinned ferromagnetic film 65 , a non-magnetic film 40 , a free ferromagnetic film 35 , a non-magnetic layer 40 , a second pinned ferromagnetic film 66 , and a second antiferromagnetic film 71 .
  • the multi-layer structure with the free layer being held between the pinned layers, causes electrons to scatter over a larger area of interface. This tends to a larger relative change of magnetoresistance ( ⁇ R/R in percent) and a larger output of reproduction.
  • This type of giant magnetoresistive sensor is called dual spin valve (SV) head.
  • FIG. 11 Another type of dual spin valve (SV) head is disclosed in Japanese Patent Laid-open No. 225925/1995. As shown in FIG. 11, it has a magnetoresistive film 30 consisting of a first free magnetic film 35 , a non-magnetic film 40 , a first ferromagnetic pinned film 65 , an antiferromagnetic film 70 , a second ferromagnetic pinned layer 66 , a non-magnetic film 40 , and a second free magnetic film 36 . As in the foregoing head, the multi-layer structure, with the antiferromagnetic film being held between the pinned layers and the free layers, causes electrons to scatter over a larger area of interface. This tends to a larger relative change of magnetoresistance ( ⁇ R/R in percent).
  • a dual spin valve film to remedy the peak asymmetry of read-back waveform is described in “PtMn dual spin valve film with a Co/Ru/Co laminated ferri pinned magnetic layer”, Synopsis of the 22 nd Lecture Meeting of Japan Institute of Applied Magnetism, p. 309. As shown in FIG. 12, it has a magnetoresistive film 30 consisting of a first antiferromagnetic film 70 , a first composite ferromagnetic film (pinned layer) 50 , a non-magnetic film 40 , a ferromagnetic film (free layer) 35 , a non-magnetic film 40 , a second composite ferromagnetic film (pinned layer) 60 , and a second antiferromagnetic film 71 .
  • the composite ferromagnetic films 50 and 60 have the same structure as the aforesaid composite film shown in FIG. 8 . This structure is intended to reduce the static magnetic field from the pinned layer, thereby remedying the peak asymmetry of the read-back waveform of the head.
  • the disadvantage of the composite film functioning as the upper and lower pinned layers in the dual spin valve head is that the overall film thickness of the magnetic head increases. Any attempt to compensate the increased thickness by reduction in the thickness of the magnetic gap layers 20 and 100 shown in FIG. 7 ends up with an insufficient electro-static durability which leads to electro-static destruction due to short-circuits between the magnetoresistive film and shield film.
  • the giant magnetoresistive sensor has a magnetoresistive film consisting of a substrate, a first free ferromagnetic film, a first non-magnetic film, a composite ferromagnetic film, a second non-magnetic film, and a second free ferromagnetic film, which are formed sequentially one over another, so that the composite ferromagnetic film becomes the pinned layer of self-pinned type.
  • the pinned layer of self-pinned type consists of a first, second, and third ferromagnetic films antiferromagnetically coupled with one another and films separating these three ferromagnetic films and antiferromagnetically coupling them with one another.
  • the giant magnetoresistive sensor may also have a magnetoresistive film consisting of a substrate, a first composite ferromagnetic film, a first non-magnetic film, a free ferromagnetic film, a second non-magnetic film, and a second composite ferromagnetic film, which are laminated one over another.
  • the aforesaid first and second composite ferromagnetic films should be the pinned layer of self-pinned type.
  • the pinned layer of self-pinned type consists of a first and second ferromagnetic films antiferromagnetically coupled with each other and a film separating these two ferromagnetic films and antiferromagnetically coupling them with each other. Either of the first and second composite ferromagnetic films may be replaced by the conventional pinned layer in which a singe pinned ferromagnetic film is pinned by an antiferromagnetic film.
  • the giant magnetoresistive sensor of the present invention is characterized in that the net amount of magnetic moment of the aforesaid composite ferromagnetic film can be made smaller than the total amount of magnetic moment of each ferromagnetic film in the composite ferromagnetic film.
  • the composite film is regarded as one magnetic entity responsible for the net magnetic moment.
  • the giant magnetoresistive sensor of the present invention may be constructed such that the first and second ferromagnetic films of the aforesaid magnetic composite layer have almost the same magnetic moment and consequently the net magnetic moment of the aforesaid composite ferromagnetic film is nearly null.
  • the giant magnetoresistive sensor of the present invention should have the aforesaid antiferromagnetic film such that it produces great unidirectional anisotropy regardless of the order of lamination of the antiferromagnetic film and the ferromagnetic film. It should preferably be made of nickel oxide, PtMn, PtPdMn, CrMnPt, or the like.
  • the giant magnetoresistive sensor of the present invention may be combined with a thin-film head of induction type for magnetic recording so as to constitute a thin-film magnetic head.
  • the giant magnetoresistive sensor of dual spin valve head type may have a composite film of self-pinned type as the pinned layer.
  • the result is a reduction of static magnetic field from the pinned layer and hence a remedy for peak asymmetry of read-back waveform.
  • Another result is a reduction of the total film thickness of the magnetoresistive film. This permits the insulating film between the magnetoresistive film and shield film to be thicker, and the thicker insulating film contributes to electro-static durability.
  • the conventional dual spin valve head shown in FIG. 11 has the disadvantage that the scattering of electrons not contributing to the relative change of magnetoresistance takes place in the antiferromagnetic film 70
  • the giant magnetoresistive sensor of the present invention shown in FIG. 1 is free from this disadvantage owing to the two free layers formed on both sides of the self-pinned layer and hence it has a better relative change of magnetoresistance than the conventional one.
  • FIG. 1 is a sectional view of the giant magnetoresistive sensor in one embodiment of the present invention.
  • FIG. 2 is a sectional view of the giant magnetoresistive sensor in another embodiment of the present invention.
  • FIG. 3 is a sectional view of the giant magnetoresistive sensor in another embodiment of the present invention.
  • FIG. 4 is a sectional view of the giant magnetoresistive sensor in another embodiment of the present invention.
  • FIG. 5 is a perspective view showing the structure of the thin-film magnetic head equipped with the giant magnetoresistive sensor of the present invention.
  • FIG. 6 is a schematic drawing of the read/write apparatus.
  • FIG. 7 is a sectional view of a conventional giant magnetoresistive sensor.
  • FIG. 8 is a sectional view showing a magnetoresistive film in a conventional giant magnetoresistive sensor with a pinned layer of composite film.
  • FIG. 9 is a sectional view showing a magnetoresistive film in a conventional giant magnetoresistive sensor with a pinned layer of composite film.
  • FIG. 10 is a sectional view showing a magnetoresistive film in a conventional giant magnetoresistive sensor of dual spin valve type.
  • FIG. 11 is a sectional view showing a magnetoresistive film in a conventional giant magnetoresistive sensor of dual spin valve type.
  • FIG. 12 is a sectional view showing a magnetoresistive film in a conventional giant magnetoresistive sensor of dual spin valve type.
  • FIG. 13 is a graph showing the dependence of the normalized output and peak asymmetry of read-out waveform on the sensor height hMR in the giant magnetoresistive sensor in the example of the present invention.
  • a typical giant magnetoresistive sensor of the present invention is shown in section in FIG. 1 .
  • a substrate 5 On the substrate 5 are formed sequentially a lower shield film (NiFe film) 10 , an insulating film (Al 2 O 3 film) 20 for magnetic gap, and a magnetoresistive film 30 .
  • the magnetoresistive film 30 is composed of a first free ferromagnetic film (NiFeCo) 35 , a copper layer 40 , a composite ferromagnetic film (pinned layer of self-pinned type) 50 , a copper layer 40 , and a second free ferromagnetic film (NiFeCo) 45 , which are sequentially formed one over another.
  • the composite ferromagnetic film (pinned layer of self-pinned type) 50 is composed of Co 51 (25 ⁇ ), Ru 52 (6 ⁇ ), Co 53 (30 ⁇ ), Ru 52 (6 ⁇ ), and Co 54 (25 ⁇ ), which are laminated sequentially.
  • a magnetic field is applied in the direction of the arrow 200 .
  • the composite ferromagnetic film has its axis of easy magnetization oriented in the direction perpendicular to the paper surface.
  • An organic resist film is laminated, and then it is patterned as desired.
  • a film of permanent magnet (CoCrPt film) 80 is laminated. It is fabricated in a desired shape.
  • a layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode 90 .
  • An insulating film (Al 2 O 3 film) 100 for magnetic gap is formed.
  • An upper shield film (NiFe film) 110 is laminated and then it is fabricated in a desired shape. Thus there is obtained a magnetic head.
  • the electrode spacing Tw is 0.5 ⁇ m and the sensor height hMR is 0.4 ⁇ m.
  • the arrows 55 in the figure denote the direction of magnetization of each magnetic film.
  • the first, second, and third ferromagnetic films are strongly coupled with one another in an antiferromagnetic manner, and hence magnetization takes place in the direction shown.
  • the composite ferromagnetic film 50 has a large effective coercive force and forms the pinned layer of self-pinned type.
  • the head of the present invention was compared with a giant magnetoresistive sensor of conventional type which has the same electrode spacing and sensor height (shown in FIG. 7 ). It was found that the head of the present invention produces 1.5 times as large read-back output as the conventional one.
  • the read-back output is the value normalized such that the value of the conventional head (with hMR being 0.4 ⁇ m) is 1.
  • the head of the present invention keeps Asym. almost null. Even when hMR changes from 0.2 ⁇ m to 0.7 ⁇ m, Asym. changes very little. This makes it possible to reduce the fluctuation of Asym. due to tolerance of hMR.
  • the read-back output is about 1.5 times larger than that in the conventional case.
  • this example gives a giant magnetoresistive sensor with small peak asymmetry and large read-back output.
  • this example gives a giant magnetoresistive sensor superior in electro-static durability.
  • Example 1 demonstrates another giant magnetoresistive sensor which differs in the thickness of the pinned layer from the one in Example 1.
  • it consists of a substrate 5 , a lower shield film (NiFe film) 10 , an insulating film (Al 2 O 3 ) 20 for magnetic gap, and a magnetoresistive film 30 .
  • the magnetoresistive film 30 consists of a first free ferromagnetic layer (NiFeCo) 35 , a copper layer 40 , a composite ferromagnetic film (pinned layer of self-pinned type) 50 , and a copper layer 40 , and a second free ferromagnetic film NiFeCo) 55 , which are laminated sequentially.
  • the composite ferromagnetic film (pinned layer of self-pinned type) 50 consists of Co 51 (20 ⁇ ), Ru 52 (6 ⁇ ), Co 53 (35 ⁇ ), Ru 52 (6 ⁇ ), and Co 54 (20 ⁇ ) , which are laminated sequentially.
  • a magnetic field is applied in the direction of the arrow 200 .
  • the composite ferromagnetic film has its axis of easy magnetization oriented in the direction perpendicular to the paper surface.
  • An organic resist film is laminated, and then it is patterned as desired.
  • a film of permanent magnet (CoCrPt film) 80 is laminated. It is fabricated in a desired shape.
  • a layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode 90 .
  • An insulating film (Al 2 O 3 film) 100 for magnetic gap is formed.
  • An upper shield film (NiFe film) 110 is laminated and then it is fabricated in a desired shape. Thus there is obtained a magnetic head.
  • the electrode spacing Tw is 0.5 ⁇ m and the sensor height hMR is 0.4 ⁇ m.
  • the composite ferromagnetic film 50 has a large effective coercive force and forms the pinned layer of self-pinned type for stable operation. It was also found that the giant magnetoresistive sensor produces 1.5 times as large read-back output as the conventional one and has good electro-static durability and good Asym.
  • This example demonstrates another giant magnetoresistive sensor whose sectional view is shown in FIG. 2 . It consists of a substrate 5 , a lower shield film (NiFe film) 10 , an insulating film (Al 2 O 3 ) 20 for magnetic gap, and a magnetoresistive film 30 .
  • the magnetoresistive film 30 consists of a first composite ferromagnetic film (pinned layer) 50 , a copper layer 40 , a free ferromagnetic film (NiFeCo) 35 , a copper layer 40 , and a second composite ferromagnetic film (pinned layer) 60 , which are laminated sequentially.
  • the first composite ferromagnetic film (pinned layer) 50 consists of Co 51 (20 ⁇ ), Ru 52 (6 ⁇ ), and Co 53 (35 ⁇ ), which are laminated sequentially. During lamination a magnetic field is applied in the direction of the arrow 200 . Owing to the applied magnetic field, the composite ferromagnetic film 50 has its axis of easy magnetization oriented in the direction perpendicular to the paper surface. The Co film 51 and the Co film 53 are strongly coupled with each other in an antiferromagnetic manner, and hence magnetization takes place in the direction shown. The composite ferromagnetic film 50 has a large effective coercive force and forms the pinned layer of self-pinned type.
  • the second composite ferromagnetic film (pinned layer) 60 consists of Co 61 (20 ⁇ ), Ru 62 (6 ⁇ ), and Co 63 (35 ⁇ ), which are laminated sequentially.
  • a magnetic field is applied in the direction of the arrow 201 .
  • the composite ferromagnetic film 60 has its axis of easy magnetization oriented in the direction perpendicular to the paper surface, and magnetization takes place in the direction shown.
  • the composite ferromagnetic film 60 forms the pinned layer of self-pinned type.
  • the first and second ferromagnetic composite films produce effective magnetic moments in their antiparallel direction. This cancels out the magnetic field applied to the free layer from the composite ferromagnetic film.
  • an organic resist film is laminated, and then it is patterned as desired.
  • a film of permanent magnet (CoCrPt film) 80 is laminated. It is fabricated in a desired shape.
  • a layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode 90 .
  • An insulating film (Al 2 O 3 film) 100 for magnetic gap is formed.
  • An upper shield film (NiFe film) 110 is laminated and then it is fabricated in a desired shape. Thus there is obtained a magnetic head.
  • the electrode spacing Tw is 0.5 ⁇ m and the sensor height hMR is 0.4 ⁇ m.
  • the giant magnetoresistive sensor produces 1.5 times as large read-back output as the conventional one and has good electro-static durability and good Asym.
  • this example also demonstrates another giant magnetoresistive sensor which is identical in structure with the above-mentioned one, except that the thickness of the Co film in the first and second composite ferromagnetic film varies so that the effective magnetic moment of the composite ferromagnetic film varies.
  • the first and second composite ferromagnetic films produce the effective magnetic moment in the same direction.
  • the first and second magnetic composite layers have the two Co films of the same thickness so that their effective magnetic moment is nearly null.
  • either of the composite ferromagnetic films has an effective magnetic moment which is almost null.
  • the resulting giant magnetoresistive sensor produces a large read-back output and has good electro-static durability and good Asym.
  • This example demonstrates another giant magnetoresistive sensor whose sectional view is shown in FIG. 3 . It consists of a substrate 5 , a lower shield film (NiFe film) 10 , an insulating film (Al 2 O 3 ) 20 for magnetic gap, and a magnetoresistive film 30 .
  • the magnetoresistive film 30 consists of a composite ferromagnetic film (pinned layer) 50 , a copper layer 40 , a free ferromagnetic film NiFeCo) 35 , a copper layer 40 , a pinned ferromagnetic film (CoFe) 65 , and an antiferromagnetic film (CrMnPt) 70 , which are laminated sequentially.
  • the composite ferromagnetic film (pinned layer) 50 consists of Co 51 (20 ⁇ ), Ru 52 (6 ⁇ ), and Co 53 (35 ⁇ ), which are laminated sequentially. During lamination a magnetic field is applied in the direction of the arrow 200 . Owing to the applied magnetic field, the composite ferromagnetic film 50 has its axis of easy magnetization oriented in the direction perpendicular to the paper surface. The Co film 51 and the Co film 53 are strongly coupled with each other in an antiferromagnetic manner, so that they form a pinned layer of self-pinned type. Subsequently, an organic resist film is laminated, and then it is patterned as desired. A film of permanent magnet (CoCrPt film) 80 is laminated.
  • a layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode 90 .
  • An insulating film (Al 2 O 3 film) 100 for magnetic gap is formed.
  • An upper shield film (NiFe film) 110 is laminated and then it is fabricated in a desired shape. Thus there is obtained a magnetic head.
  • the electrode spacing Tw is 0.5 ⁇ m and the sensor height hMR is 0.4 ⁇ m.
  • the pinned ferromagnetic layer 65 is magnetized in the direction of the arrow 55 .
  • this direction may be reversed (180°).
  • the giant magnetoresistive sensor in this example produces 1.5 times as large read-back output as the conventional one and has good electro-static durability and good Asym.
  • this example also demonstrates another giant magnetoresistive sensor which is identical in structure with the above-mentioned one, except that the thickness of the ferromagnetic film is changed (Co 20 ⁇ , Ru 6 ⁇ , Co 25 ⁇ ) so that the effective magnetic moment of the composite ferromagnetic film 50 is almost null.
  • the giant magnetoresistive sensor produces a large read-back output and has good electro-static durability and good Asym.
  • This example demonstrates another giant magnetoresistive sensor whose sectional view is shown in FIG. 4 . It consists of a substrate 5 , a lower shield film (NiFe film) 10 , an insulating film (Al 2 O 3 ) 20 for magnetic gap, and a magnetoresistive film 30 .
  • the magnetoresistive film 30 consists of an antiferromagnetic layer (CrMnPt) 70 , a pinned ferromagnetic layer (CoFe) 65 , a copper layer 40 , a free ferromagnetic layer (NiFeCo) 35 , a copper layer 40 , and a composite ferromagnetic film (pinned layer) 50 , which are laminated sequentially.
  • the composite ferromagnetic film (pinned layer) 50 consists of Co 51 (35 ⁇ ), Ru 52 (6 ⁇ ), and Co 53 (20 ⁇ ), which are laminated sequentially.
  • a magnetic field is applied in the direction of the arrow 200 .
  • the composite ferromagnetic film 50 has its axis of easy magnetization oriented in the direction perpendicular to the paper surface.
  • the Co film 51 and the Co film 53 are strongly coupled with each other in an antiferromagnetic manner, so that they form a pinned layer of self-pinned type.
  • an organic resist film is laminated, and then it is patterned as desired.
  • a film of permanent magnet (CoCrPt film) 80 is laminated.
  • a layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode 90 .
  • An insulating film (Al 2 O 3 film) 100 for magnetic gap is formed.
  • An upper shield film (NiFe film) 110 is laminated and then it is fabricated in a desired shape. Thus there is obtained a magnetic head.
  • the electrode spacing Tw is 0.5 ⁇ m and the sensor height hMR is 0.4 ⁇ m.
  • the pinned ferromagnetic layer 65 is magnetized in the direction of the arrow 55 .
  • this direction may be reversed (180°).
  • the composite ferromagnetic film 50 produces an effective coercive force and hence forms the pinned layer of self-pinned type.
  • the giant magnetoresistive sensor in this example produces 1.5 times as large read-back output as the conventional one and has good electro-static durability and good Asym.
  • this example also demonstrates another giant magnetoresistive sensor which is identical in structure with the above-mentioned one, except that the thickness of the ferromagnetic layer is changed (Co 25 ⁇ , Ru 6 ⁇ , Co 20 ⁇ ) so that the effective magnetic moment of the composite ferromagnetic film 50 is almost null.
  • the giant magnetoresistive sensor produces a large read-back output and has good electro-static durability and good Asym.
  • This example demonstrates another giant magnetoresistive sensor having an antiferromagnetic layer as in Example 4. It consists of a substrate, a lower shield film (NiFe film) 5 , an insulating film (Al 2 O 3 ) 10 for magnetic gap, and a magnetoresistive film 30 .
  • the magnetoresistive film 30 consists of a composite ferromagnetic film (pinned layer) 50 , a copper layer 40 , a pinned ferromagnetic layer (CoFe) 65 , and an antiferromagnetic layer (PtMn) 70 , which are laminated sequentially.
  • the composite ferromagnetic film (pinned layer) 50 consists of Co 51 (20 ⁇ ), Ru 52 (6 ⁇ ), and Co 53 (35 ⁇ ), which are laminated sequentially.
  • the composite ferromagnetic film 50 has its axis of easy magnetization oriented in the direction perpendicular to the paper surface.
  • the Co film 51 and the Co film 53 are strongly coupled with each other in an antiferromagnetic manner, so that they form a pinned layer of self-pinned type.
  • an organic resist film is laminated, and then it is patterned as desired.
  • a film of permanent magnet (CoCrPt film) 80 is laminated. It is fabricated in a desired shape.
  • a layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode.
  • An insulating film (Al 2 O 3 film) for magnetic gap is formed.
  • An upper shield film (NiFe film) is laminated and then it is fabricated in a desired shape. Thus there is obtained a magnetic head.
  • the giant magnetoresistive sensor in this example produces 1.5 times as large read-back output as the conventional one and has good electro-static durability and good Asym.
  • FIG. 5 is a partly cut away perspective view showing this thin-film magnetic head.
  • a substrate 5 (as a slider) which is a sintered body composed mainly of Al 2 O 3 .TiC.
  • a lower shield film 10 On the substrate are formed a lower shield film 10 and an insulating film (Al 2 O 3 film) for magnetic gap.
  • a magnetoresistive film 30 which consists of a first free ferromagnetic film (NiFeCo), a copper layer, a composite ferromagnetic film (pinned layer of self-pinned type), a copper layer, and a second free ferromagnetic film (NiFeCo), which are laminated sequentially.
  • the ferromagnetic composite film (pinned layer of self-pinned type) is composed of Co (20 ⁇ ), Ru (6 ⁇ ), Co (35 ⁇ ), Ru (6 ⁇ ), and Co (20 ⁇ ), which are laminated sequentially. Subsequently, an organic resist film is laminated, and then it is patterned as desired. A film of permanent magnet (CoCrPt film) is laminated.
  • a layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode.
  • An insulating film (Al 2 O 3 film) for magnetic gap is formed.
  • a magnetic shield film (NiFe film) 110 is formed. The part produced as mentioned above functions as the reading head.
  • An inductive thin-film head is formed as the magnetic writing head, which consists of an upper magnetic pole 120 and a coil 130 .
  • the upper magnetic pole 120 is a 3.0- ⁇ m thick film of Ni-20 at % Fe alloy which is formed by sputtering.
  • the gap between the upper shield film 110 and the upper magnetic pole 120 is filled with a 0.2- ⁇ m thick Al 2 O 3 film formed by sputtering.
  • the coil 130 is a 3.0- ⁇ m thick copper film.
  • the lower magnetic pole 110 and the upper magnetic pole 120 are magnetically connected with each other to form a magnetic circuit.
  • the coil 130 intersects the magnetic circuit.
  • the thin-film magnetic head of this example produces 1.5 times as large read-back output as the conventional one and has good peak symmetry of read-back waveform, with Asym. depending on hMR very little.
  • This example demonstrates a magnetic disk apparatus equipped with the magnetic head produced in the aforesaid examples of the present invention. It is schematically shown in FIG. 6 .
  • a magnetic recording medium 140 which is made of a Co—Ni—Pt—Ta alloy having a residual magnetic flux density of 0.45 T.
  • the magnetic recording medium 140 is driven by a drive unit 150 .
  • the magnetic head 160 is driven by the drive unit 170 so that it selects any track on the magnetic recording medium 140 .
  • Signals for the magnetic head 160 are processed by the read/write signal processing system 180 .
  • the magnetoresistive sensor built into the magnetic head 160 produces a larger reproduction output and better peak symmetry of read-back waveform than the magnetoresistive sensor of conventional structure. Therefore, the magnetic disk apparatus equipped with it has a narrow track width and a high recording density.
  • the present invention provides a giant magnetoresistive sensor which produces a large reproduction output, good peak symmetry of read-back waveform, and good electro-static durability.

Abstract

A giant magnetoresistive sensor which is improved in reproduction output and peak asymmetry of read-back waveform. It is composed of a first free ferromagnetic film, a first non-magnetic film, a composite ferromagnetic film, a second non-magnetic film, and a second free ferromagnetic film, which are laminated sequentially, but has no antiferromagnetic film to fix said composite ferromagnetic film, and said composite ferromagnetic film contains a first, second, and third ferromagnetic film, which are antiferromagnetically coupled with one another, and also contains films which separate said ferromagnetic films from one another and antiferromagnetically couple them with one another.

Description

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head to record and reproduce information on and from a magnetic recording medium, and more particularly to an improved giant magnetoresistive sensor and a magnetic recording/reproducing apparatus equipped with said sensor.
2. Description of the Related Art
The increasing magnetic recording density requires a highly sensitive magnetic head for reproduction. The one meeting this requirement is described in “Giant magnetoresistance in soft magnetic multi-layer film”, Physical Review B, vol. 43, pp. 1297-1300. It is constructed such that two magnetic layers are separated by one nonmagnetic layer and an exchange bias magnetic field is applied to one of the magnetic layers from an antiferromagnetic layer. This type of multi-layer film has resistance R with a component varying in proportion to cosθ, with θ being an angle between the directions of magnetization of the two magnetic layers, according to the aforesaid thesis. This phenomenon is referred to as giant magnetoresistance (GMR).
A conventional giant magnetoresistive sensor is shown in FIG. 7. It consists of a substrate 5 and several layers sequentially formed thereon. Adjacent to the substrate are a magnetic shield layer 10 and a magnetic gap layer 20. On the magnetic gap layer 20 is a magnetoresistive film 30, which consists of a ferromagnetic film (free layer) 35, a copper layer 40, a ferromagnetic film (pinned layer) 65, and an antiferromagnetic film 70, which are formed sequentially one over another. The arrow 55 indicates the direction of magnetization. With the magnetoresistive film 30 patterned, there are arranged an electrode film 90 and a permanent magnet layer 80 at each side thereof. The top is covered with a magnetic gap layer 100 and a magnetic shield layer 110. The magnetoresistive film mentioned above is characterized in that the pinned layer has its magnetization pinned in the direction of element height (depth) by the exchange bias magnetic field from the antiferromagnetic layer. In general, the free layer has the axis of easy magnetization parallel to the cross-track direction (z direction) of the head.
In the case of the head mentioned above, it is desirable that the magnetization in the entire free layer be kept parallel to the cross-track direction of the head so that the free layer does not suffer magnetic saturation when a signal magnetic field from the medium is applied upward and downward in the direction of the element height of the head. Unfortunately, the magnetization in the free layer does not become uniformly parallel to the cross-track direction of the head because the free layer receives a static magnetic field which occurs as the pinned layer (orienting vertically to the medium surface) becomes magnetized. The result is that the head becomes sensitive unequally to the positive and negative magnetic fields and reproduces a large peak asymmetry of read-back waveform. This not only adversely affects the improvement of error rate by signal processing such as PRML (partial response sampling plus maximum likelihood detection) but also lowers the output. The peak asymmetry of read-back waveform is defined as follows.
Asym.=|V + −V − |/|V + +V −|
(where V+ denotes the peak value of the positive output and V− denotes the peak value of the negative output.)
There is disclosed in Japanese Patent Laid-open No. 169026/1995 a giant magnetoresistive sensor designed to reduce the peak asymmetry of read-back waveform. As shown in FIG. 8, it has a magnetoresistive film 30 consisting of a ferromagnetic film (free layer) 35, a copper layer 40, a composite ferromagnetic film (pinned layer) 50, and an antiferromagnetic film 70. The pinned layer 50, which is a composite ferromagnetic film, consists of two ferromagnetic films 51 and 53 (of Co or the like) and a non-magnetic layer 52 (or Ru or the like), the former having their magnetization strongly coupled in the antiparallel direction through the latter. The two ferromagnetic films produce magnetic moments aligning in the antiparallel direction, thereby canceling out each other. The result is a reduction of static magnetic field applied to the free layer from the pinned layer. The second ferromagnetic film 53 of the pinned layer 50 has its magnetization pinned by the antiferromagnetic film 70.
There is disclosed in Japanese Patent Laid-open No. 7235/1996 another giant magnetoresistive sensor designed to reduce the peak asymmetry of read-back waveform. As shown in FIG. 9, it has a magnetoresistive film 30 consisting of a ferromagnetic film (free layer) 35, a copper layer 40, and a composite ferromagnetic film (pinned layer) 50. The pinned layer 50, which is a composite ferromagnetic film, consists of two ferromagnetic films 51 and 53 (of Co or the like) and a non-magnetic layer 52 (or Ru or the like), the former having their magnetization strongly coupled in the antiparallel direction through the latter, like the aforesaid head. The two ferromagnetic films 51 and 53 should have an adequate thickness, so that the pinned layer has a large effective coercive force for it to be of self-pinned type. The result is a reduction of static magnetic field applied from the pinned layer and obviation of the antiferromagnetic film to fix the pinned layer. The advantage is a reduction of the entire film thickness of the head and a reduction of the gap length.
On the other hand, there is disclosed in Japanese Patent Laid-open No. 347013/1993 and U.S. Pat. No. 5,287,238 a giant magnetoresistive sensor designed to increase its reproducing output. As shown in FIG. 10, it has a magnetoresistive film 30 consisting of a first antiferromagnetic layer 70, a first pinned ferromagnetic film 65, a non-magnetic film 40, a free ferromagnetic film 35, a non-magnetic layer 40, a second pinned ferromagnetic film 66, and a second antiferromagnetic film 71. The multi-layer structure, with the free layer being held between the pinned layers, causes electrons to scatter over a larger area of interface. This tends to a larger relative change of magnetoresistance (ΔR/R in percent) and a larger output of reproduction. This type of giant magnetoresistive sensor is called dual spin valve (SV) head.
Another type of dual spin valve (SV) head is disclosed in Japanese Patent Laid-open No. 225925/1995. As shown in FIG. 11, it has a magnetoresistive film 30 consisting of a first free magnetic film 35, a non-magnetic film 40, a first ferromagnetic pinned film 65, an antiferromagnetic film 70, a second ferromagnetic pinned layer 66, a non-magnetic film 40, and a second free magnetic film 36. As in the foregoing head, the multi-layer structure, with the antiferromagnetic film being held between the pinned layers and the free layers, causes electrons to scatter over a larger area of interface. This tends to a larger relative change of magnetoresistance (ΔR/R in percent).
SUMMARY OF THE INVENTION
The disadvantage of the aforesaid structure, with the free layer or antiferromagnetic film being held between two upper and lower pinned layers, is that the static magnetic field applied to the thickness of the free layer from the pinned layer increases as the pinned layer increases. Consequently, the direction of magnetization of the free layer deviates from the direction of the track width of the head, with the result that the peak asymmetry of reproduced signals becomes larger. The larger the asymmetry, the lower the read-back output.
A dual spin valve film to remedy the peak asymmetry of read-back waveform is described in “PtMn dual spin valve film with a Co/Ru/Co laminated ferri pinned magnetic layer”, Synopsis of the 22nd Lecture Meeting of Japan Institute of Applied Magnetism, p. 309. As shown in FIG. 12, it has a magnetoresistive film 30 consisting of a first antiferromagnetic film 70, a first composite ferromagnetic film (pinned layer) 50, a non-magnetic film 40, a ferromagnetic film (free layer) 35, a non-magnetic film 40, a second composite ferromagnetic film (pinned layer) 60, and a second antiferromagnetic film 71. The composite ferromagnetic films 50 and 60 have the same structure as the aforesaid composite film shown in FIG. 8. This structure is intended to reduce the static magnetic field from the pinned layer, thereby remedying the peak asymmetry of the read-back waveform of the head.
The disadvantage of the composite film functioning as the upper and lower pinned layers in the dual spin valve head is that the overall film thickness of the magnetic head increases. Any attempt to compensate the increased thickness by reduction in the thickness of the magnetic gap layers 20 and 100 shown in FIG. 7 ends up with an insufficient electro-static durability which leads to electro-static destruction due to short-circuits between the magnetoresistive film and shield film.
It is an object of the present invention to provide a giant magnetoresistive sensor of dual spin valve type which excels in electro-static durability and peak symmetry of read-back waveform.
The giant magnetoresistive sensor has a magnetoresistive film consisting of a substrate, a first free ferromagnetic film, a first non-magnetic film, a composite ferromagnetic film, a second non-magnetic film, and a second free ferromagnetic film, which are formed sequentially one over another, so that the composite ferromagnetic film becomes the pinned layer of self-pinned type. The pinned layer of self-pinned type consists of a first, second, and third ferromagnetic films antiferromagnetically coupled with one another and films separating these three ferromagnetic films and antiferromagnetically coupling them with one another.
According to the present invention, the giant magnetoresistive sensor may also have a magnetoresistive film consisting of a substrate, a first composite ferromagnetic film, a first non-magnetic film, a free ferromagnetic film, a second non-magnetic film, and a second composite ferromagnetic film, which are laminated one over another. The aforesaid first and second composite ferromagnetic films should be the pinned layer of self-pinned type. The pinned layer of self-pinned type consists of a first and second ferromagnetic films antiferromagnetically coupled with each other and a film separating these two ferromagnetic films and antiferromagnetically coupling them with each other. Either of the first and second composite ferromagnetic films may be replaced by the conventional pinned layer in which a singe pinned ferromagnetic film is pinned by an antiferromagnetic film.
The giant magnetoresistive sensor of the present invention is characterized in that the net amount of magnetic moment of the aforesaid composite ferromagnetic film can be made smaller than the total amount of magnetic moment of each ferromagnetic film in the composite ferromagnetic film. The composite film is regarded as one magnetic entity responsible for the net magnetic moment.
Also, the giant magnetoresistive sensor of the present invention may be constructed such that the first and second ferromagnetic films of the aforesaid magnetic composite layer have almost the same magnetic moment and consequently the net magnetic moment of the aforesaid composite ferromagnetic film is nearly null.
The giant magnetoresistive sensor of the present invention should have the aforesaid antiferromagnetic film such that it produces great unidirectional anisotropy regardless of the order of lamination of the antiferromagnetic film and the ferromagnetic film. It should preferably be made of nickel oxide, PtMn, PtPdMn, CrMnPt, or the like.
In addition, the giant magnetoresistive sensor of the present invention may be combined with a thin-film head of induction type for magnetic recording so as to constitute a thin-film magnetic head.
The giant magnetoresistive sensor of dual spin valve head type may have a composite film of self-pinned type as the pinned layer. The result is a reduction of static magnetic field from the pinned layer and hence a remedy for peak asymmetry of read-back waveform. Another result is a reduction of the total film thickness of the magnetoresistive film. This permits the insulating film between the magnetoresistive film and shield film to be thicker, and the thicker insulating film contributes to electro-static durability.
While the conventional dual spin valve head shown in FIG. 11 has the disadvantage that the scattering of electrons not contributing to the relative change of magnetoresistance takes place in the antiferromagnetic film 70, the giant magnetoresistive sensor of the present invention shown in FIG. 1 is free from this disadvantage owing to the two free layers formed on both sides of the self-pinned layer and hence it has a better relative change of magnetoresistance than the conventional one.
In addition, according to the present invention, it is possible to control the peak symmetry of read-back waveform if the static magnetic field applied to the free layer from the pinned layer is regulated by changing the difference in thickness of the two or three ferromagnetic films in the composite film of the pinned layer of self-pinned type.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of the giant magnetoresistive sensor in one embodiment of the present invention.
FIG. 2 is a sectional view of the giant magnetoresistive sensor in another embodiment of the present invention.
FIG. 3 is a sectional view of the giant magnetoresistive sensor in another embodiment of the present invention.
FIG. 4 is a sectional view of the giant magnetoresistive sensor in another embodiment of the present invention.
FIG. 5 is a perspective view showing the structure of the thin-film magnetic head equipped with the giant magnetoresistive sensor of the present invention.
FIG. 6 is a schematic drawing of the read/write apparatus.
FIG. 7 is a sectional view of a conventional giant magnetoresistive sensor.
FIG. 8 is a sectional view showing a magnetoresistive film in a conventional giant magnetoresistive sensor with a pinned layer of composite film.
FIG. 9 is a sectional view showing a magnetoresistive film in a conventional giant magnetoresistive sensor with a pinned layer of composite film.
FIG. 10 is a sectional view showing a magnetoresistive film in a conventional giant magnetoresistive sensor of dual spin valve type.
FIG. 11 is a sectional view showing a magnetoresistive film in a conventional giant magnetoresistive sensor of dual spin valve type.
FIG. 12 is a sectional view showing a magnetoresistive film in a conventional giant magnetoresistive sensor of dual spin valve type.
FIG. 13 is a graph showing the dependence of the normalized output and peak asymmetry of read-out waveform on the sensor height hMR in the giant magnetoresistive sensor in the example of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The invention will be described in more detail with reference to the following examples.
EXAMPLE 1
A typical giant magnetoresistive sensor of the present invention is shown in section in FIG. 1. There is shown a substrate 5. On the substrate 5 are formed sequentially a lower shield film (NiFe film) 10, an insulating film (Al2O3 film) 20 for magnetic gap, and a magnetoresistive film 30. The magnetoresistive film 30 is composed of a first free ferromagnetic film (NiFeCo) 35, a copper layer 40, a composite ferromagnetic film (pinned layer of self-pinned type) 50, a copper layer 40, and a second free ferromagnetic film (NiFeCo) 45, which are sequentially formed one over another. The composite ferromagnetic film (pinned layer of self-pinned type) 50 is composed of Co 51 (25 Å), Ru 52 (6 Å), Co 53 (30 Å), Ru 52 (6 Å), and Co 54 (25 Å), which are laminated sequentially. During lamination a magnetic field is applied in the direction of the arrow 200. Owing to the applied magnetic field, the composite ferromagnetic film has its axis of easy magnetization oriented in the direction perpendicular to the paper surface. An organic resist film is laminated, and then it is patterned as desired. A film of permanent magnet (CoCrPt film) 80 is laminated. It is fabricated in a desired shape. A layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode 90. An insulating film (Al2O3 film) 100 for magnetic gap is formed. An upper shield film (NiFe film) 110 is laminated and then it is fabricated in a desired shape. Thus there is obtained a magnetic head. The electrode spacing Tw is 0.5 μm and the sensor height hMR is 0.4 μm.
The arrows 55 in the figure denote the direction of magnetization of each magnetic film. In the composite ferromagnetic film 50, the first, second, and third ferromagnetic films are strongly coupled with one another in an antiferromagnetic manner, and hence magnetization takes place in the direction shown. The composite ferromagnetic film 50 has a large effective coercive force and forms the pinned layer of self-pinned type.
The head of the present invention was compared with a giant magnetoresistive sensor of conventional type which has the same electrode spacing and sensor height (shown in FIG. 7). It was found that the head of the present invention produces 1.5 times as large read-back output as the conventional one.
A large number of heads varying in hMR were prepared, and they were tested for peak-asymmetry of read-back waveform (Asym.) and read-back output. The results are shown in FIG. 13. Asym. is defined as follows:
Asym.=|V + −V − |/|V + +V −|
(where V+ denotes the peak value of the positive output and V− denotes the peak value of the negative output.) The read-back output is the value normalized such that the value of the conventional head (with hMR being 0.4 μm) is 1. In the case of the conventional head, it is difficult to make Asym. null. In addition, Asym. greatly changes as hMR changes. By contrast, the head of the present invention keeps Asym. almost null. Even when hMR changes from 0.2 μm to 0.7 μm, Asym. changes very little. This makes it possible to reduce the fluctuation of Asym. due to tolerance of hMR. The read-back output is about 1.5 times larger than that in the conventional case. As mentioned above, this example gives a giant magnetoresistive sensor with small peak asymmetry and large read-back output. In addition, this example gives a giant magnetoresistive sensor superior in electro-static durability.
EXAMPLE 2
This example demonstrates another giant magnetoresistive sensor which differs in the thickness of the pinned layer from the one in Example 1. As in Example 1 shown in FIG. 1, it consists of a substrate 5, a lower shield film (NiFe film) 10, an insulating film (Al2O3) 20 for magnetic gap, and a magnetoresistive film 30. The magnetoresistive film 30 consists of a first free ferromagnetic layer (NiFeCo) 35, a copper layer 40, a composite ferromagnetic film (pinned layer of self-pinned type) 50, and a copper layer 40, and a second free ferromagnetic film NiFeCo) 55, which are laminated sequentially. The composite ferromagnetic film (pinned layer of self-pinned type) 50 consists of Co 51 (20 Å), Ru 52 (6 Å), Co 53 (35 Å), Ru 52 (6 Å), and Co 54 (20 Å) , which are laminated sequentially. During lamination a magnetic field is applied in the direction of the arrow 200. Owing to the applied magnetic field, the composite ferromagnetic film has its axis of easy magnetization oriented in the direction perpendicular to the paper surface. An organic resist film is laminated, and then it is patterned as desired. A film of permanent magnet (CoCrPt film) 80 is laminated. It is fabricated in a desired shape. A layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode 90. An insulating film (Al2O3 film) 100 for magnetic gap is formed. An upper shield film (NiFe film) 110 is laminated and then it is fabricated in a desired shape. Thus there is obtained a magnetic head. The electrode spacing Tw is 0.5 μm and the sensor height hMR is 0.4 μm.
It was found that in this example, too, the composite ferromagnetic film 50 has a large effective coercive force and forms the pinned layer of self-pinned type for stable operation. It was also found that the giant magnetoresistive sensor produces 1.5 times as large read-back output as the conventional one and has good electro-static durability and good Asym.
EXAMPLE 3
This example demonstrates another giant magnetoresistive sensor whose sectional view is shown in FIG. 2. It consists of a substrate 5, a lower shield film (NiFe film) 10, an insulating film (Al2O3) 20 for magnetic gap, and a magnetoresistive film 30. The magnetoresistive film 30 consists of a first composite ferromagnetic film (pinned layer) 50, a copper layer 40, a free ferromagnetic film (NiFeCo) 35, a copper layer 40, and a second composite ferromagnetic film (pinned layer) 60, which are laminated sequentially. The first composite ferromagnetic film (pinned layer) 50 consists of Co 51 (20 Å), Ru 52 (6 Å), and Co 53 (35 Å), which are laminated sequentially. During lamination a magnetic field is applied in the direction of the arrow 200. Owing to the applied magnetic field, the composite ferromagnetic film 50 has its axis of easy magnetization oriented in the direction perpendicular to the paper surface. The Co film 51 and the Co film 53 are strongly coupled with each other in an antiferromagnetic manner, and hence magnetization takes place in the direction shown. The composite ferromagnetic film 50 has a large effective coercive force and forms the pinned layer of self-pinned type. Likewise, the second composite ferromagnetic film (pinned layer) 60 consists of Co 61 (20 Å), Ru 62 (6 Å), and Co 63 (35 Å), which are laminated sequentially. During lamination a magnetic field is applied in the direction of the arrow 201. Owing to the applied magnetic field, the composite ferromagnetic film 60 has its axis of easy magnetization oriented in the direction perpendicular to the paper surface, and magnetization takes place in the direction shown. As in the case of the composite ferromagnetic film 50, the composite ferromagnetic film 60 forms the pinned layer of self-pinned type. The first and second ferromagnetic composite films produce effective magnetic moments in their antiparallel direction. This cancels out the magnetic field applied to the free layer from the composite ferromagnetic film.
Subsequently, an organic resist film is laminated, and then it is patterned as desired. A film of permanent magnet (CoCrPt film) 80 is laminated. It is fabricated in a desired shape. A layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode 90. An insulating film (Al2O3 film) 100 for magnetic gap is formed. An upper shield film (NiFe film) 110 is laminated and then it is fabricated in a desired shape. Thus there is obtained a magnetic head. The electrode spacing Tw is 0.5 μm and the sensor height hMR is 0.4 μm.
It was found that in this example, too, the giant magnetoresistive sensor produces 1.5 times as large read-back output as the conventional one and has good electro-static durability and good Asym.
Further, this example also demonstrates another giant magnetoresistive sensor which is identical in structure with the above-mentioned one, except that the thickness of the Co film in the first and second composite ferromagnetic film varies so that the effective magnetic moment of the composite ferromagnetic film varies. In the first case, the first and second composite ferromagnetic films produce the effective magnetic moment in the same direction. In the second case, the first and second magnetic composite layers have the two Co films of the same thickness so that their effective magnetic moment is nearly null. In the third case, either of the composite ferromagnetic films has an effective magnetic moment which is almost null. In all the cases, the resulting giant magnetoresistive sensor produces a large read-back output and has good electro-static durability and good Asym.
EXAMPLE 4
This example demonstrates another giant magnetoresistive sensor whose sectional view is shown in FIG. 3. It consists of a substrate 5, a lower shield film (NiFe film) 10, an insulating film (Al2O3) 20 for magnetic gap, and a magnetoresistive film 30. The magnetoresistive film 30 consists of a composite ferromagnetic film (pinned layer) 50, a copper layer 40, a free ferromagnetic film NiFeCo) 35, a copper layer 40, a pinned ferromagnetic film (CoFe) 65, and an antiferromagnetic film (CrMnPt) 70, which are laminated sequentially. The composite ferromagnetic film (pinned layer) 50 consists of Co 51 (20 Å), Ru 52 (6 Å), and Co 53 (35 Å), which are laminated sequentially. During lamination a magnetic field is applied in the direction of the arrow 200. Owing to the applied magnetic field, the composite ferromagnetic film 50 has its axis of easy magnetization oriented in the direction perpendicular to the paper surface. The Co film 51 and the Co film 53 are strongly coupled with each other in an antiferromagnetic manner, so that they form a pinned layer of self-pinned type. Subsequently, an organic resist film is laminated, and then it is patterned as desired. A film of permanent magnet (CoCrPt film) 80 is laminated. It is fabricated in a desired shape. A layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode 90. An insulating film (Al2O3 film) 100 for magnetic gap is formed. An upper shield film (NiFe film) 110 is laminated and then it is fabricated in a desired shape. Thus there is obtained a magnetic head. The electrode spacing Tw is 0.5 μm and the sensor height hMR is 0.4 μm.
In this example, the pinned ferromagnetic layer 65 is magnetized in the direction of the arrow 55. However, this direction may be reversed (180°).
It was found that the giant magnetoresistive sensor in this example produces 1.5 times as large read-back output as the conventional one and has good electro-static durability and good Asym.
Further, this example also demonstrates another giant magnetoresistive sensor which is identical in structure with the above-mentioned one, except that the thickness of the ferromagnetic film is changed (Co 20 Å, Ru 6 Å, Co 25 Å) so that the effective magnetic moment of the composite ferromagnetic film 50 is almost null. The giant magnetoresistive sensor produces a large read-back output and has good electro-static durability and good Asym.
EXAMPLE 5
This example demonstrates another giant magnetoresistive sensor whose sectional view is shown in FIG. 4. It consists of a substrate 5, a lower shield film (NiFe film) 10, an insulating film (Al2O3) 20 for magnetic gap, and a magnetoresistive film 30. The magnetoresistive film 30 consists of an antiferromagnetic layer (CrMnPt) 70, a pinned ferromagnetic layer (CoFe) 65, a copper layer 40, a free ferromagnetic layer (NiFeCo) 35, a copper layer 40, and a composite ferromagnetic film (pinned layer) 50, which are laminated sequentially. The composite ferromagnetic film (pinned layer) 50 consists of Co 51 (35 Å), Ru 52 (6 Å), and Co 53 (20 Å), which are laminated sequentially. During lamination a magnetic field is applied in the direction of the arrow 200. Owing to the applied magnetic field, the composite ferromagnetic film 50 has its axis of easy magnetization oriented in the direction perpendicular to the paper surface. The Co film 51 and the Co film 53 are strongly coupled with each other in an antiferromagnetic manner, so that they form a pinned layer of self-pinned type. Subsequently, an organic resist film is laminated, and then it is patterned as desired. A film of permanent magnet (CoCrPt film) 80 is laminated. It is fabricated in a desired shape. A layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode 90. An insulating film (Al2O3 film) 100 for magnetic gap is formed. An upper shield film (NiFe film) 110 is laminated and then it is fabricated in a desired shape. Thus there is obtained a magnetic head. The electrode spacing Tw is 0.5 μm and the sensor height hMR is 0.4 μm.
In this example, the pinned ferromagnetic layer 65 is magnetized in the direction of the arrow 55. However, this direction may be reversed (180°). The composite ferromagnetic film 50 produces an effective coercive force and hence forms the pinned layer of self-pinned type.
It was found that the giant magnetoresistive sensor in this example produces 1.5 times as large read-back output as the conventional one and has good electro-static durability and good Asym.
Further, this example also demonstrates another giant magnetoresistive sensor which is identical in structure with the above-mentioned one, except that the thickness of the ferromagnetic layer is changed (Co 25 Å, Ru 6 Å, Co 20 Å) so that the effective magnetic moment of the composite ferromagnetic film 50 is almost null. The giant magnetoresistive sensor produces a large read-back output and has good electro-static durability and good Asym.
EXAMPLE 6
This example demonstrates another giant magnetoresistive sensor having an antiferromagnetic layer as in Example 4. It consists of a substrate, a lower shield film (NiFe film) 5, an insulating film (Al2O3) 10 for magnetic gap, and a magnetoresistive film 30. The magnetoresistive film 30 consists of a composite ferromagnetic film (pinned layer) 50, a copper layer 40, a pinned ferromagnetic layer (CoFe) 65, and an antiferromagnetic layer (PtMn) 70, which are laminated sequentially. The composite ferromagnetic film (pinned layer) 50 consists of Co 51 (20 Å), Ru 52 (6 Å), and Co 53 (35 Å), which are laminated sequentially. The composite ferromagnetic film 50 has its axis of easy magnetization oriented in the direction perpendicular to the paper surface. The Co film 51 and the Co film 53 are strongly coupled with each other in an antiferromagnetic manner, so that they form a pinned layer of self-pinned type. Subsequently, an organic resist film is laminated, and then it is patterned as desired. A film of permanent magnet (CoCrPt film) 80 is laminated. It is fabricated in a desired shape. A layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode. An insulating film (Al2O3 film) for magnetic gap is formed. An upper shield film (NiFe film) is laminated and then it is fabricated in a desired shape. Thus there is obtained a magnetic head.
The giant magnetoresistive sensor in this example produces 1.5 times as large read-back output as the conventional one and has good electro-static durability and good Asym.
EXAMPLE 7
This example demonstrates a thin-film magnetic head (of read/write separate type) in which the magnetoresistance element of the present invention is used as the reading head and the conventional inductive thin-film head is used as the writing head. FIG. 5 is a partly cut away perspective view showing this thin-film magnetic head. There is shown a substrate 5 (as a slider) which is a sintered body composed mainly of Al2O3.TiC. On the substrate are formed a lower shield film 10 and an insulating film (Al2O3 film) for magnetic gap. On them is further formed a magnetoresistive film 30, which consists of a first free ferromagnetic film (NiFeCo), a copper layer, a composite ferromagnetic film (pinned layer of self-pinned type), a copper layer, and a second free ferromagnetic film (NiFeCo), which are laminated sequentially. The ferromagnetic composite film (pinned layer of self-pinned type) is composed of Co (20 Å), Ru (6 Å), Co (35 Å), Ru (6 Å), and Co (20 Å), which are laminated sequentially. Subsequently, an organic resist film is laminated, and then it is patterned as desired. A film of permanent magnet (CoCrPt film) is laminated. It is fabricated in a desired shape. A layer of Nb/Au/Nb is laminated, and then it is fabricated to form an electrode. An insulating film (Al2O3 film) for magnetic gap is formed. A magnetic shield film (NiFe film) 110 is formed. The part produced as mentioned above functions as the reading head.
An inductive thin-film head is formed as the magnetic writing head, which consists of an upper magnetic pole 120 and a coil 130. The upper magnetic pole 120 is a 3.0-μm thick film of Ni-20 at % Fe alloy which is formed by sputtering. The gap between the upper shield film 110 and the upper magnetic pole 120 is filled with a 0.2-μm thick Al2O3 film formed by sputtering. The coil 130 is a 3.0-μm thick copper film. The lower magnetic pole 110 and the upper magnetic pole 120 are magnetically connected with each other to form a magnetic circuit. The coil 130 intersects the magnetic circuit.
It was found that the thin-film magnetic head of this example produces 1.5 times as large read-back output as the conventional one and has good peak symmetry of read-back waveform, with Asym. depending on hMR very little.
EXAMPLE 8
This example demonstrates a magnetic disk apparatus equipped with the magnetic head produced in the aforesaid examples of the present invention. It is schematically shown in FIG. 6.
There is shown a magnetic recording medium 140, which is made of a Co—Ni—Pt—Ta alloy having a residual magnetic flux density of 0.45 T. The magnetic recording medium 140 is driven by a drive unit 150. The magnetic head 160 is driven by the drive unit 170 so that it selects any track on the magnetic recording medium 140. Signals for the magnetic head 160 are processed by the read/write signal processing system 180.
The magnetoresistive sensor built into the magnetic head 160 produces a larger reproduction output and better peak symmetry of read-back waveform than the magnetoresistive sensor of conventional structure. Therefore, the magnetic disk apparatus equipped with it has a narrow track width and a high recording density.
As mentioned above, the present invention provides a giant magnetoresistive sensor which produces a large reproduction output, good peak symmetry of read-back waveform, and good electro-static durability.

Claims (8)

What is claimed is:
1. A giant magnetoresistive sensor having a magnetoresistive film, a pair of electrodes to supply electric current to said magnetoresistive film, and magnetic shield films formed on the upper and lower sides of said magnetoresistive film, characterized in that said magnetoresistive film is composed of a first free ferromagnetic film, a first non-magnetic film, a composite ferromagnetic film, a second non-magnetic film, and a second free ferromagnetic film, which are laminated sequentially, and said composite ferromagnetic film contains a first, second, and third ferromagnetic films, which are antiferromagnetically coupled with one another, and also contains films which separate said ferromagnetic films from one another and antiferromagnetically couple them with one another.
2. A giant magnetoresistive sensor as defined in claim 1, wherein the net magnetic moment of said composite ferromagnetic film is smaller than the magnetic moments in total of the first, second, and third ferromagnetic films constituting said composite ferromagnetic film.
3. A giant magnetoresistive sensor as defined in claim 1, wherein the total amount of magnetic moment of the first and third ferromagnetic films of said composite ferromagnetic film is approximately equal to the magnetic moment of the second ferromagnetic film.
4. A giant magnetoresistive sensor having a magnetoresistive film, a pair of electrodes to supply electric current to said magnetoresistive film, and magnetic shield films formed on the upper and lower sides of said magnetoresistive film, characterized in that said magnetoresistive film is composed of a first composite ferromagnetic film, a first non-magnetic film, a free ferromagnetic film, and a second composite ferromagnetic film, which are laminated sequentially, and said first composite ferromagnetic film and said second composite ferromagnetic film contain a first and second ferromagnetic films, which are antiferromagnetically coupled with each other, and also contain films which separate said ferromagnetic films from each other and antiferromagnetically couple them with each other.
5. A giant magnetoresistive sensor as defined in claim 4, wherein the net magnetic moment of said first composite ferromagnetic film is smaller than the magnetic moments in total of the first and second magnetic films constituting said first composite ferromagnetic film and the net magnetic moment of said second composite ferromagnetic film is smaller than the magnetic moments in total of the first and second magnetic films constituting said second composite ferromagnetic film.
6. A giant magnetoresistive sensor as defined in claim 4, wherein the magnetic moments of the first and second ferromagnetic films of said first or second composite ferromagnetic films are approximately equal to each other.
7. A thin-film read/write head which comprises an inductive thin-film head for magnetic recording and a giant magnetoresistive sensor as defined in claim 1, said inductive thin-film head having a pair of magnetic poles, a magnetic circuit to magnetically couple said pair of magnetic poles, and a coil intersecting said magnetic circuit.
8. A magnetic recording apparatus which comprises a magnetic recording medium, a thin-film magnetic head mentioned in claim 7, a drive means to drive said magnetic recording medium and said head relatively to each other, and a read/write signal processor connected to said head.
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Cited By (98)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020018323A1 (en) * 2000-04-12 2002-02-14 Shaoping Li Dual pseudo spin valve heads
US20020036874A1 (en) * 2000-08-04 2002-03-28 Tdk Corporation Magnetoresistive device and method of manufacturing same and thin-film magnetic head and method of manufacturing same
US20020036497A1 (en) * 2000-08-04 2002-03-28 Tdk Corporation Magnetoresistive device and method of manufacturing same and thin-film magnetic head and method of manufacturing same
US6603713B1 (en) 2000-07-28 2003-08-05 Terastor Corporation Optical disk drives with thermomagnetic writing and magnetoresistive reading
US20030197976A1 (en) * 2002-04-18 2003-10-23 Van Der Heijden Petrus A. Perpendicular magnetic recording head with improved write field gradient
US6661624B1 (en) * 1999-09-28 2003-12-09 Fujitsu Limited Spin-valve magnetoresistive device having a layer for canceling a leakage magnetic field
US20030227722A1 (en) * 2002-04-18 2003-12-11 International Business Machines Corporation Spin valve sensor with dual self-pinned AP pinned layer structures
US6667682B2 (en) 2001-12-26 2003-12-23 Honeywell International Inc. System and method for using magneto-resistive sensors as dual purpose sensors
US20040008450A1 (en) * 2002-07-15 2004-01-15 International Business Machines Corporation CPP sensor with dual self-pinned AP pinned layer structures
US6721131B2 (en) 2001-03-15 2004-04-13 Seagate Technology Llc Composite write pole for a magnetic recording head
US20040141262A1 (en) * 2000-07-06 2004-07-22 Hiromasa Takahashi Magnetoresistive sensor including magnetic domain control layers having high electric resistivity, magnetic head and magnetic disk apparatus
US20040165319A1 (en) * 2003-02-20 2004-08-26 Honeywell International Inc. Magnetic field sensor
US6801412B2 (en) 2002-04-19 2004-10-05 International Business Machines Corporation Method and apparatus for improved pinning strength for self-pinned giant magnetoresistive heads
US6865062B2 (en) 2002-03-21 2005-03-08 International Business Machines Corporation Spin valve sensor with exchange biased free layer and antiparallel (AP) pinned layer pinned without a pinning layer
US20050167657A1 (en) * 2000-03-09 2005-08-04 Nickel Janice H. Multi-bit magnetic memory cells
US20050219770A1 (en) * 2004-03-31 2005-10-06 Hitachi Global Storage Technologies Double tunnel junction using self-pinned center ferromagnet
US20060152858A1 (en) * 2005-01-10 2006-07-13 Hitachi Global Storage Technologies Netherlands, B.V. Three terminal magnetic sensor having an in-stack longitudinal biasing layer structure and a self-pinned layer structure
WO2009059071A3 (en) * 2007-10-31 2009-10-22 New York University High speed low power magnetic devices based on current induced spin-momentum transfer
US20090296462A1 (en) * 2003-08-19 2009-12-03 New York University High speed low power magnetic devices based on current induced spin-momentum transfer
US8755222B2 (en) 2003-08-19 2014-06-17 New York University Bipolar spin-transfer switching
US8982613B2 (en) 2013-06-17 2015-03-17 New York University Scalable orthogonal spin transfer magnetic random access memory devices with reduced write error rates
US9082950B2 (en) 2012-10-17 2015-07-14 New York University Increased magnetoresistance in an inverted orthogonal spin transfer layer stack
US9082888B2 (en) 2012-10-17 2015-07-14 New York University Inverted orthogonal spin transfer layer stack
US9263667B1 (en) 2014-07-25 2016-02-16 Spin Transfer Technologies, Inc. Method for manufacturing MTJ memory device
US9337412B2 (en) 2014-09-22 2016-05-10 Spin Transfer Technologies, Inc. Magnetic tunnel junction structure for MRAM device
US9728712B2 (en) 2015-04-21 2017-08-08 Spin Transfer Technologies, Inc. Spin transfer torque structure for MRAM devices having a spin current injection capping layer
US9741926B1 (en) 2016-01-28 2017-08-22 Spin Transfer Technologies, Inc. Memory cell having magnetic tunnel junction and thermal stability enhancement layer
US9773974B2 (en) 2015-07-30 2017-09-26 Spin Transfer Technologies, Inc. Polishing stop layer(s) for processing arrays of semiconductor elements
US9812184B2 (en) 2007-10-31 2017-11-07 New York University Current induced spin-momentum transfer stack with dual insulating layers
US9853206B2 (en) 2015-06-16 2017-12-26 Spin Transfer Technologies, Inc. Precessional spin current structure for MRAM
US10032978B1 (en) 2017-06-27 2018-07-24 Spin Transfer Technologies, Inc. MRAM with reduced stray magnetic fields
US10141499B1 (en) 2017-12-30 2018-11-27 Spin Transfer Technologies, Inc. Perpendicular magnetic tunnel junction device with offset precessional spin current layer
US10163479B2 (en) 2015-08-14 2018-12-25 Spin Transfer Technologies, Inc. Method and apparatus for bipolar memory write-verify
US10199083B1 (en) 2017-12-29 2019-02-05 Spin Transfer Technologies, Inc. Three-terminal MRAM with ac write-assist for low read disturb
US10229724B1 (en) 2017-12-30 2019-03-12 Spin Memory, Inc. Microwave write-assist in series-interconnected orthogonal STT-MRAM devices
US10236439B1 (en) 2017-12-30 2019-03-19 Spin Memory, Inc. Switching and stability control for perpendicular magnetic tunnel junction device
US10236047B1 (en) 2017-12-29 2019-03-19 Spin Memory, Inc. Shared oscillator (STNO) for MRAM array write-assist in orthogonal STT-MRAM
US10236048B1 (en) 2017-12-29 2019-03-19 Spin Memory, Inc. AC current write-assist in orthogonal STT-MRAM
US10255962B1 (en) 2017-12-30 2019-04-09 Spin Memory, Inc. Microwave write-assist in orthogonal STT-MRAM
US10270027B1 (en) 2017-12-29 2019-04-23 Spin Memory, Inc. Self-generating AC current assist in orthogonal STT-MRAM
US10319900B1 (en) 2017-12-30 2019-06-11 Spin Memory, Inc. Perpendicular magnetic tunnel junction device with precessional spin current layer having a modulated moment density
US10339993B1 (en) 2017-12-30 2019-07-02 Spin Memory, Inc. Perpendicular magnetic tunnel junction device with skyrmionic assist layers for free layer switching
US10360961B1 (en) 2017-12-29 2019-07-23 Spin Memory, Inc. AC current pre-charge write-assist in orthogonal STT-MRAM
US10360962B1 (en) 2017-12-28 2019-07-23 Spin Memory, Inc. Memory array with individually trimmable sense amplifiers
US10360964B2 (en) 2016-09-27 2019-07-23 Spin Memory, Inc. Method of writing contents in memory during a power up sequence using a dynamic redundancy register in a memory device
US10367139B2 (en) 2017-12-29 2019-07-30 Spin Memory, Inc. Methods of manufacturing magnetic tunnel junction devices
US10366774B2 (en) 2016-09-27 2019-07-30 Spin Memory, Inc. Device with dynamic redundancy registers
US10388861B1 (en) 2018-03-08 2019-08-20 Spin Memory, Inc. Magnetic tunnel junction wafer adaptor used in magnetic annealing furnace and method of using the same
US10395712B2 (en) 2017-12-28 2019-08-27 Spin Memory, Inc. Memory array with horizontal source line and sacrificial bitline per virtual source
US10395711B2 (en) 2017-12-28 2019-08-27 Spin Memory, Inc. Perpendicular source and bit lines for an MRAM array
US10411185B1 (en) 2018-05-30 2019-09-10 Spin Memory, Inc. Process for creating a high density magnetic tunnel junction array test platform
US10424723B2 (en) 2017-12-29 2019-09-24 Spin Memory, Inc. Magnetic tunnel junction devices including an optimization layer
US10424726B2 (en) 2017-12-28 2019-09-24 Spin Memory, Inc. Process for improving photoresist pillar adhesion during MRAM fabrication
US10438995B2 (en) 2018-01-08 2019-10-08 Spin Memory, Inc. Devices including magnetic tunnel junctions integrated with selectors
US10438996B2 (en) 2018-01-08 2019-10-08 Spin Memory, Inc. Methods of fabricating magnetic tunnel junctions integrated with selectors
US10437491B2 (en) 2016-09-27 2019-10-08 Spin Memory, Inc. Method of processing incomplete memory operations in a memory device during a power up sequence and a power down sequence using a dynamic redundancy register
US10437723B2 (en) 2016-09-27 2019-10-08 Spin Memory, Inc. Method of flushing the contents of a dynamic redundancy register to a secure storage area during a power down in a memory device
US10446744B2 (en) 2018-03-08 2019-10-15 Spin Memory, Inc. Magnetic tunnel junction wafer adaptor used in magnetic annealing furnace and method of using the same
US10446210B2 (en) 2016-09-27 2019-10-15 Spin Memory, Inc. Memory instruction pipeline with a pre-read stage for a write operation for reducing power consumption in a memory device that uses dynamic redundancy registers
US10460781B2 (en) 2016-09-27 2019-10-29 Spin Memory, Inc. Memory device with a dual Y-multiplexer structure for performing two simultaneous operations on the same row of a memory bank
US10468590B2 (en) 2015-04-21 2019-11-05 Spin Memory, Inc. High annealing temperature perpendicular magnetic anisotropy structure for magnetic random access memory
US10468588B2 (en) 2018-01-05 2019-11-05 Spin Memory, Inc. Perpendicular magnetic tunnel junction device with skyrmionic enhancement layers for the precessional spin current magnetic layer
US10481976B2 (en) 2017-10-24 2019-11-19 Spin Memory, Inc. Forcing bits as bad to widen the window between the distributions of acceptable high and low resistive bits thereby lowering the margin and increasing the speed of the sense amplifiers
US10489245B2 (en) 2017-10-24 2019-11-26 Spin Memory, Inc. Forcing stuck bits, waterfall bits, shunt bits and low TMR bits to short during testing and using on-the-fly bit failure detection and bit redundancy remapping techniques to correct them
US10516094B2 (en) 2017-12-28 2019-12-24 Spin Memory, Inc. Process for creating dense pillars using multiple exposures for MRAM fabrication
US10529439B2 (en) 2017-10-24 2020-01-07 Spin Memory, Inc. On-the-fly bit failure detection and bit redundancy remapping techniques to correct for fixed bit defects
US10529915B2 (en) 2018-03-23 2020-01-07 Spin Memory, Inc. Bit line structures for three-dimensional arrays with magnetic tunnel junction devices including an annular free magnetic layer and a planar reference magnetic layer
US10546625B2 (en) 2016-09-27 2020-01-28 Spin Memory, Inc. Method of optimizing write voltage based on error buffer occupancy
US10546624B2 (en) 2017-12-29 2020-01-28 Spin Memory, Inc. Multi-port random access memory
US10559338B2 (en) 2018-07-06 2020-02-11 Spin Memory, Inc. Multi-bit cell read-out techniques
US10580827B1 (en) 2018-11-16 2020-03-03 Spin Memory, Inc. Adjustable stabilizer/polarizer method for MRAM with enhanced stability and efficient switching
US10593396B2 (en) 2018-07-06 2020-03-17 Spin Memory, Inc. Multi-bit cell read-out techniques for MRAM cells with mixed pinned magnetization orientations
US10600478B2 (en) 2018-07-06 2020-03-24 Spin Memory, Inc. Multi-bit cell read-out techniques for MRAM cells with mixed pinned magnetization orientations
US10628316B2 (en) 2016-09-27 2020-04-21 Spin Memory, Inc. Memory device with a plurality of memory banks where each memory bank is associated with a corresponding memory instruction pipeline and a dynamic redundancy register
US10650875B2 (en) 2018-08-21 2020-05-12 Spin Memory, Inc. System for a wide temperature range nonvolatile memory
US10656994B2 (en) 2017-10-24 2020-05-19 Spin Memory, Inc. Over-voltage write operation of tunnel magnet-resistance (“TMR”) memory device and correcting failure bits therefrom by using on-the-fly bit failure detection and bit redundancy remapping techniques
US10665777B2 (en) 2017-02-28 2020-05-26 Spin Memory, Inc. Precessional spin current structure with non-magnetic insertion layer for MRAM
US10672976B2 (en) 2017-02-28 2020-06-02 Spin Memory, Inc. Precessional spin current structure with high in-plane magnetization for MRAM
US10679685B2 (en) 2017-12-27 2020-06-09 Spin Memory, Inc. Shared bit line array architecture for magnetoresistive memory
US10692569B2 (en) 2018-07-06 2020-06-23 Spin Memory, Inc. Read-out techniques for multi-bit cells
US10699761B2 (en) 2018-09-18 2020-06-30 Spin Memory, Inc. Word line decoder memory architecture
US10784437B2 (en) 2018-03-23 2020-09-22 Spin Memory, Inc. Three-dimensional arrays with MTJ devices including a free magnetic trench layer and a planar reference magnetic layer
US10784439B2 (en) 2017-12-29 2020-09-22 Spin Memory, Inc. Precessional spin current magnetic tunnel junction devices and methods of manufacture
US10811594B2 (en) 2017-12-28 2020-10-20 Spin Memory, Inc. Process for hard mask development for MRAM pillar formation using photolithography
US10818331B2 (en) 2016-09-27 2020-10-27 Spin Memory, Inc. Multi-chip module for MRAM devices with levels of dynamic redundancy registers
US10840436B2 (en) 2017-12-29 2020-11-17 Spin Memory, Inc. Perpendicular magnetic anisotropy interface tunnel junction devices and methods of manufacture
US10840439B2 (en) 2017-12-29 2020-11-17 Spin Memory, Inc. Magnetic tunnel junction (MTJ) fabrication methods and systems
US10886330B2 (en) 2017-12-29 2021-01-05 Spin Memory, Inc. Memory device having overlapping magnetic tunnel junctions in compliance with a reference pitch
US10891997B2 (en) 2017-12-28 2021-01-12 Spin Memory, Inc. Memory array with horizontal source line and a virtual source line
US10971680B2 (en) 2018-10-01 2021-04-06 Spin Memory, Inc. Multi terminal device stack formation methods
US10991410B2 (en) 2016-09-27 2021-04-27 Spin Memory, Inc. Bi-polar write scheme
US11107974B2 (en) 2018-03-23 2021-08-31 Spin Memory, Inc. Magnetic tunnel junction devices including a free magnetic trench layer and a planar reference magnetic layer
US11107978B2 (en) 2018-03-23 2021-08-31 Spin Memory, Inc. Methods of manufacturing three-dimensional arrays with MTJ devices including a free magnetic trench layer and a planar reference magnetic layer
US11107979B2 (en) 2018-12-28 2021-08-31 Spin Memory, Inc. Patterned silicide structures and methods of manufacture
US11119910B2 (en) 2016-09-27 2021-09-14 Spin Memory, Inc. Heuristics for selecting subsegments for entry in and entry out operations in an error cache system with coarse and fine grain segments
US11119936B2 (en) 2016-09-27 2021-09-14 Spin Memory, Inc. Error cache system with coarse and fine segments for power optimization
US11151042B2 (en) 2016-09-27 2021-10-19 Integrated Silicon Solution, (Cayman) Inc. Error cache segmentation for power reduction
US11621293B2 (en) 2018-10-01 2023-04-04 Integrated Silicon Solution, (Cayman) Inc. Multi terminal device stack systems and methods

Families Citing this family (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7289303B1 (en) * 2001-04-05 2007-10-30 Western Digital (Fremont), Llc Spin valve sensors having synthetic antiferromagnet for longitudinal bias
US6744086B2 (en) 2001-05-15 2004-06-01 Nve Corporation Current switched magnetoresistive memory cell
WO2003098632A2 (en) * 2002-05-16 2003-11-27 Nova Research, Inc. Methods of fabricating magnetoresistive memory devices
US6680828B2 (en) * 2002-06-07 2004-01-20 International Business Machines Corporation Differential GMR head system and method using self-pinned layer
US6713800B2 (en) * 2002-06-27 2004-03-30 Seagate Technology Llc Magnetoresistive sensor with reduced side-reading effect
US6888742B1 (en) * 2002-08-28 2005-05-03 Grandis, Inc. Off-axis pinned layer magnetic element utilizing spin transfer and an MRAM device using the magnetic element
JP4419408B2 (en) * 2003-03-14 2010-02-24 Ｔｄｋ株式会社 Magnetoresistive element and magnetic memory device
US7230804B2 (en) * 2003-05-02 2007-06-12 Hitachi Global Storage Technologies Netherlands B.V. Method and apparatus for providing a magnetic tunnel transistor with a self-pinned emitter
US7916435B1 (en) 2003-05-02 2011-03-29 Hitachi Global Storage Technologies Netherlands B.V. Magnetic tunnel transistor having a base structure that provides polarization of unpolarized electrons from an emitter based upon a magnetic orientation of a free layer and a self-pinned layer
US7019950B2 (en) * 2003-06-17 2006-03-28 Hitachi Global Storage Technologies, Netherlands, B.V. Magnetoresistive sensor having bias magnets with steep endwalls
US7064935B2 (en) * 2003-06-17 2006-06-20 Hitachi Global Storage Technologies Netherland B.V. Magnetoresistive sensor having leads with vertical end walls
US6989975B2 (en) * 2003-06-18 2006-01-24 Hewlett-Packard Development Company, L.P. Magnetoresistive device including pinned structure with a layer that provides texture for pinning
US7092220B2 (en) * 2003-07-29 2006-08-15 Hitachi Global Storage Technologies Apparatus for enhancing thermal stability, improving biasing and reducing damage from electrostatic discharge in self-pinned abutted junction heads having a first self-pinned layer extending under the hard bias layers
US7119997B2 (en) * 2003-09-30 2006-10-10 Hitachi Global Storage Technologies Netherlands B.V. Spin valve sensor having an antiparallel (AP) self-pinned layer structure comprising cobalt for high magnetostriction
US7177122B2 (en) * 2003-10-27 2007-02-13 Seagate Technology Llc Biasing for tri-layer magnetoresistive sensors
US7151653B2 (en) * 2004-02-18 2006-12-19 Hitachi Global Technologies Netherlands B.V. Depositing a pinned layer structure in a self-pinned spin valve
US7463459B2 (en) 2004-02-18 2008-12-09 Hitachi Global Storage Technologies Netherlands B.V. Self-pinned read sensor design with enhanced lead stabilizing mechanism
US7538988B2 (en) * 2004-09-30 2009-05-26 Hitachi Global Storage Technologies Netherlands B.V. Method and apparatus having improved magnetic read head sensors

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5206590A (en) * 1990-12-11 1993-04-27 International Business Machines Corporation Magnetoresistive sensor based on the spin valve effect
JPH05347013A (en) 1992-04-13 1993-12-27 Hitachi Ltd Magnetic recording and reproducing device
JPH07169026A (en) 1993-10-15 1995-07-04 Internatl Business Mach Corp <Ibm> Magnetoresistance spin valve sensor and magnetic recording system using said sensor
JPH07225925A (en) 1994-02-07 1995-08-22 Fujitsu Ltd Magneto-resistance sensor
JPH087235A (en) 1994-06-15 1996-01-12 Internatl Business Mach Corp <Ibm> Spin-valve magnetoresistance element and related device
US5828531A (en) * 1996-09-18 1998-10-27 International Business Machines Corporation Spin valve sensor with enhanced magnetoresistance
US5883764A (en) * 1997-10-03 1999-03-16 International Business Machines Corporation Magnetoresistive sensor having multi-layered refractory metal conductor leads
US5910344A (en) * 1996-10-07 1999-06-08 Alps Electric Co., Ltd. Method of manufacturing a magnetoresistive sensor
US5920446A (en) * 1998-01-06 1999-07-06 International Business Machines Corporation Ultra high density GMR sensor

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5768069A (en) * 1996-11-27 1998-06-16 International Business Machines Corporation Self-biased dual spin valve sensor
US6219209B1 (en) * 1999-07-29 2001-04-17 International Business Machines Corporation Spin valve head with multiple antiparallel coupling layers

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5206590A (en) * 1990-12-11 1993-04-27 International Business Machines Corporation Magnetoresistive sensor based on the spin valve effect
JPH05347013A (en) 1992-04-13 1993-12-27 Hitachi Ltd Magnetic recording and reproducing device
JPH07169026A (en) 1993-10-15 1995-07-04 Internatl Business Mach Corp <Ibm> Magnetoresistance spin valve sensor and magnetic recording system using said sensor
US5465185A (en) 1993-10-15 1995-11-07 International Business Machines Corporation Magnetoresistive spin valve sensor with improved pinned ferromagnetic layer and magnetic recording system using the sensor
JPH07225925A (en) 1994-02-07 1995-08-22 Fujitsu Ltd Magneto-resistance sensor
JPH087235A (en) 1994-06-15 1996-01-12 Internatl Business Mach Corp <Ibm> Spin-valve magnetoresistance element and related device
US5583725A (en) 1994-06-15 1996-12-10 International Business Machines Corporation Spin valve magnetoresistive sensor with self-pinned laminated layer and magnetic recording system using the sensor
US5828531A (en) * 1996-09-18 1998-10-27 International Business Machines Corporation Spin valve sensor with enhanced magnetoresistance
US5910344A (en) * 1996-10-07 1999-06-08 Alps Electric Co., Ltd. Method of manufacturing a magnetoresistive sensor
US5883764A (en) * 1997-10-03 1999-03-16 International Business Machines Corporation Magnetoresistive sensor having multi-layered refractory metal conductor leads
US5920446A (en) * 1998-01-06 1999-07-06 International Business Machines Corporation Ultra high density GMR sensor

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
B. Dieny et al, "Giant Magnetoresistance in Soft Ferromagnetic Multilayers", Physical Review B, vol. 43, No. 1, Jan. 1991, pp. 1297-1300.
M. Saito et al, "PtMn Dual Spin Valve Films Using Co/Ru/Co Synthetic Ferrimagnet Pinned Layers", Synopsis of the 22nd Lecture Meeting of Japan Institute of Applied Magnetism, 1998, p. 309.

Cited By (138)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6661624B1 (en) * 1999-09-28 2003-12-09 Fujitsu Limited Spin-valve magnetoresistive device having a layer for canceling a leakage magnetic field
US20050167657A1 (en) * 2000-03-09 2005-08-04 Nickel Janice H. Multi-bit magnetic memory cells
US6731473B2 (en) * 2000-04-12 2004-05-04 Seagate Technology Llc Dual pseudo spin valve heads
US20020018323A1 (en) * 2000-04-12 2002-02-14 Shaoping Li Dual pseudo spin valve heads
US20050254182A1 (en) * 2000-07-06 2005-11-17 Hiromasa Takahashi Magnetoresistive sensor including magnetic domain control layers having high electric resistivity, magnetic head and magnetic disk apparatus
US7072155B2 (en) 2000-07-06 2006-07-04 Hitachi Global Storage Technologies Japan, Ltd. Magnetoresistive sensor including magnetic domain control layers having high electric resistivity, magnetic head and magnetic disk apparatus
US6947316B2 (en) * 2000-07-06 2005-09-20 Hitachi, Ltd. Magnetoresistive sensor including magnetic domain control layers having high electric resistivity, magnetic head and magnetic disk apparatus
US20040141262A1 (en) * 2000-07-06 2004-07-22 Hiromasa Takahashi Magnetoresistive sensor including magnetic domain control layers having high electric resistivity, magnetic head and magnetic disk apparatus
US6603713B1 (en) 2000-07-28 2003-08-05 Terastor Corporation Optical disk drives with thermomagnetic writing and magnetoresistive reading
US20020036497A1 (en) * 2000-08-04 2002-03-28 Tdk Corporation Magnetoresistive device and method of manufacturing same and thin-film magnetic head and method of manufacturing same
US7027271B2 (en) * 2000-08-04 2006-04-11 Tdk Corporation Magnetoresistive device in a thin-film magnetic head and method of manufacturing same having particular electrode overlay configuration
US20020036874A1 (en) * 2000-08-04 2002-03-28 Tdk Corporation Magnetoresistive device and method of manufacturing same and thin-film magnetic head and method of manufacturing same
US6721131B2 (en) 2001-03-15 2004-04-13 Seagate Technology Llc Composite write pole for a magnetic recording head
US6667682B2 (en) 2001-12-26 2003-12-23 Honeywell International Inc. System and method for using magneto-resistive sensors as dual purpose sensors
US6865062B2 (en) 2002-03-21 2005-03-08 International Business Machines Corporation Spin valve sensor with exchange biased free layer and antiparallel (AP) pinned layer pinned without a pinning layer
US6785102B2 (en) * 2002-04-18 2004-08-31 Hitachi Global Storage Technologies Netherlands B.V. Spin valve sensor with dual self-pinned AP pinned layer structures
US6813115B2 (en) * 2002-04-18 2004-11-02 Seagate Technology Llc Perpendicular magnetic recording head with improved write field gradient
US20030227722A1 (en) * 2002-04-18 2003-12-11 International Business Machines Corporation Spin valve sensor with dual self-pinned AP pinned layer structures
US20030197976A1 (en) * 2002-04-18 2003-10-23 Van Der Heijden Petrus A. Perpendicular magnetic recording head with improved write field gradient
US6801412B2 (en) 2002-04-19 2004-10-05 International Business Machines Corporation Method and apparatus for improved pinning strength for self-pinned giant magnetoresistive heads
US6781798B2 (en) * 2002-07-15 2004-08-24 International Business Machines Corporation CPP sensor with dual self-pinned AP pinned layer structures
US20040008450A1 (en) * 2002-07-15 2004-01-15 International Business Machines Corporation CPP sensor with dual self-pinned AP pinned layer structures
US20060039091A1 (en) * 2003-02-20 2006-02-23 Honeywell International Inc. System and method for fixing a direction of magnetization of pinned layers in a magnetic field sensor
US20040165319A1 (en) * 2003-02-20 2004-08-26 Honeywell International Inc. Magnetic field sensor
US7016163B2 (en) 2003-02-20 2006-03-21 Honeywell International Inc. Magnetic field sensor
US20060039090A1 (en) * 2003-02-20 2006-02-23 Honeywell International Inc. System and method for fixing a direction of magnetization of pinned layers in a magnetic field sensor
US7064937B2 (en) 2003-02-20 2006-06-20 Honeywell International Inc. System and method for fixing a direction of magnetization of pinned layers in a magnetic field sensor
US20090296462A1 (en) * 2003-08-19 2009-12-03 New York University High speed low power magnetic devices based on current induced spin-momentum transfer
US9236103B2 (en) 2003-08-19 2016-01-12 New York University Bipolar spin-transfer switching
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US8760915B2 (en) 2003-08-19 2014-06-24 New York University High speed low power magnetic devices based on current induced spin-momentum transfer
US9449668B2 (en) 2003-08-19 2016-09-20 New York University Current induced spin-momentum transfer stack with dual insulating layers
US7268986B2 (en) * 2004-03-31 2007-09-11 Hitachi Global Storage Technologies Netherlands B.V. Double tunnel junction using self-pinned center ferromagnet
US20050219770A1 (en) * 2004-03-31 2005-10-06 Hitachi Global Storage Technologies Double tunnel junction using self-pinned center ferromagnet
US20060152858A1 (en) * 2005-01-10 2006-07-13 Hitachi Global Storage Technologies Netherlands, B.V. Three terminal magnetic sensor having an in-stack longitudinal biasing layer structure and a self-pinned layer structure
US7636223B2 (en) * 2005-01-10 2009-12-22 Hitachi Global Storage Technologies Netherlands B.V. Three terminal magnetic sensor having an in-stack longitudinal biasing layer structure and a self-pinned layer structure
WO2009059071A3 (en) * 2007-10-31 2009-10-22 New York University High speed low power magnetic devices based on current induced spin-momentum transfer
US9812184B2 (en) 2007-10-31 2017-11-07 New York University Current induced spin-momentum transfer stack with dual insulating layers
CN102460697A (en) * 2009-06-24 2012-05-16 纽约大学 High speed low power magnetic devices based on current induced spin-momentum transfer
CN102460697B (en) * 2009-06-24 2014-10-29 纽约大学 High speed low power magnetic devices based on current induced spin-momentum transfer
WO2011005484A3 (en) * 2009-06-24 2011-03-03 New York University High speed low power magnetic devices based on current induced spin-momentum transfer
US9082950B2 (en) 2012-10-17 2015-07-14 New York University Increased magnetoresistance in an inverted orthogonal spin transfer layer stack
US9082888B2 (en) 2012-10-17 2015-07-14 New York University Inverted orthogonal spin transfer layer stack
US8982613B2 (en) 2013-06-17 2015-03-17 New York University Scalable orthogonal spin transfer magnetic random access memory devices with reduced write error rates
US9773837B2 (en) 2013-06-17 2017-09-26 New York University Scalable orthogonal spin transfer magnetic random access memory devices with reduced write error rates
US9263667B1 (en) 2014-07-25 2016-02-16 Spin Transfer Technologies, Inc. Method for manufacturing MTJ memory device
US9406876B2 (en) 2014-07-25 2016-08-02 Spin Transfer Technologies, Inc. Method for manufacturing MTJ memory device
US9337412B2 (en) 2014-09-22 2016-05-10 Spin Transfer Technologies, Inc. Magnetic tunnel junction structure for MRAM device
US9728712B2 (en) 2015-04-21 2017-08-08 Spin Transfer Technologies, Inc. Spin transfer torque structure for MRAM devices having a spin current injection capping layer
US10734574B2 (en) 2015-04-21 2020-08-04 Spin Memory, Inc. Method of manufacturing high annealing temperature perpendicular magnetic anisotropy structure for magnetic random access memory
US10147872B2 (en) 2015-04-21 2018-12-04 Spin Transfer Technologies, Inc. Spin transfer torque structure for MRAM devices having a spin current injection capping layer
US10468590B2 (en) 2015-04-21 2019-11-05 Spin Memory, Inc. High annealing temperature perpendicular magnetic anisotropy structure for magnetic random access memory
US10615335B2 (en) 2015-04-21 2020-04-07 Spin Memory, Inc. Spin transfer torque structure for MRAM devices having a spin current injection capping layer
US10026892B2 (en) 2015-06-16 2018-07-17 Spin Transfer Technologies, Inc. Precessional spin current structure for MRAM
US9853206B2 (en) 2015-06-16 2017-12-26 Spin Transfer Technologies, Inc. Precessional spin current structure for MRAM
US10553787B2 (en) 2015-06-16 2020-02-04 Spin Memory, Inc. Precessional spin current structure for MRAM
US9773974B2 (en) 2015-07-30 2017-09-26 Spin Transfer Technologies, Inc. Polishing stop layer(s) for processing arrays of semiconductor elements
US10777736B2 (en) 2015-07-30 2020-09-15 Spin Memory, Inc. Polishing stop layer(s) for processing arrays of semiconductor elements
US10163479B2 (en) 2015-08-14 2018-12-25 Spin Transfer Technologies, Inc. Method and apparatus for bipolar memory write-verify
US10347314B2 (en) 2015-08-14 2019-07-09 Spin Memory, Inc. Method and apparatus for bipolar memory write-verify
US9741926B1 (en) 2016-01-28 2017-08-22 Spin Transfer Technologies, Inc. Memory cell having magnetic tunnel junction and thermal stability enhancement layer
US10643680B2 (en) 2016-01-28 2020-05-05 Spin Memory, Inc. Memory cell having magnetic tunnel junction and thermal stability enhancement layer
US10381553B2 (en) 2016-01-28 2019-08-13 Spin Transfer Technologies, Inc. Memory cell having magnetic tunnel junction and thermal stability enhancement layer
US10366774B2 (en) 2016-09-27 2019-07-30 Spin Memory, Inc. Device with dynamic redundancy registers
US10424393B2 (en) 2016-09-27 2019-09-24 Spin Memory, Inc. Method of reading data from a memory device using multiple levels of dynamic redundancy registers
US10546625B2 (en) 2016-09-27 2020-01-28 Spin Memory, Inc. Method of optimizing write voltage based on error buffer occupancy
US10628316B2 (en) 2016-09-27 2020-04-21 Spin Memory, Inc. Memory device with a plurality of memory banks where each memory bank is associated with a corresponding memory instruction pipeline and a dynamic redundancy register
US10460781B2 (en) 2016-09-27 2019-10-29 Spin Memory, Inc. Memory device with a dual Y-multiplexer structure for performing two simultaneous operations on the same row of a memory bank
US10446210B2 (en) 2016-09-27 2019-10-15 Spin Memory, Inc. Memory instruction pipeline with a pre-read stage for a write operation for reducing power consumption in a memory device that uses dynamic redundancy registers
US10360964B2 (en) 2016-09-27 2019-07-23 Spin Memory, Inc. Method of writing contents in memory during a power up sequence using a dynamic redundancy register in a memory device
US10991410B2 (en) 2016-09-27 2021-04-27 Spin Memory, Inc. Bi-polar write scheme
US11119910B2 (en) 2016-09-27 2021-09-14 Spin Memory, Inc. Heuristics for selecting subsegments for entry in and entry out operations in an error cache system with coarse and fine grain segments
US10366775B2 (en) 2016-09-27 2019-07-30 Spin Memory, Inc. Memory device using levels of dynamic redundancy registers for writing a data word that failed a write operation
US11119936B2 (en) 2016-09-27 2021-09-14 Spin Memory, Inc. Error cache system with coarse and fine segments for power optimization
US11151042B2 (en) 2016-09-27 2021-10-19 Integrated Silicon Solution, (Cayman) Inc. Error cache segmentation for power reduction
US10437723B2 (en) 2016-09-27 2019-10-08 Spin Memory, Inc. Method of flushing the contents of a dynamic redundancy register to a secure storage area during a power down in a memory device
US10437491B2 (en) 2016-09-27 2019-10-08 Spin Memory, Inc. Method of processing incomplete memory operations in a memory device during a power up sequence and a power down sequence using a dynamic redundancy register
US10818331B2 (en) 2016-09-27 2020-10-27 Spin Memory, Inc. Multi-chip module for MRAM devices with levels of dynamic redundancy registers
US11271149B2 (en) 2017-02-28 2022-03-08 Integrated Silicon Solution, (Cayman) Inc. Precessional spin current structure with nonmagnetic insertion layer for MRAM
US10672976B2 (en) 2017-02-28 2020-06-02 Spin Memory, Inc. Precessional spin current structure with high in-plane magnetization for MRAM
US10665777B2 (en) 2017-02-28 2020-05-26 Spin Memory, Inc. Precessional spin current structure with non-magnetic insertion layer for MRAM
US11355699B2 (en) 2017-02-28 2022-06-07 Integrated Silicon Solution, (Cayman) Inc. Precessional spin current structure for MRAM
US10032978B1 (en) 2017-06-27 2018-07-24 Spin Transfer Technologies, Inc. MRAM with reduced stray magnetic fields
US10481976B2 (en) 2017-10-24 2019-11-19 Spin Memory, Inc. Forcing bits as bad to widen the window between the distributions of acceptable high and low resistive bits thereby lowering the margin and increasing the speed of the sense amplifiers
US10656994B2 (en) 2017-10-24 2020-05-19 Spin Memory, Inc. Over-voltage write operation of tunnel magnet-resistance (“TMR”) memory device and correcting failure bits therefrom by using on-the-fly bit failure detection and bit redundancy remapping techniques
US10489245B2 (en) 2017-10-24 2019-11-26 Spin Memory, Inc. Forcing stuck bits, waterfall bits, shunt bits and low TMR bits to short during testing and using on-the-fly bit failure detection and bit redundancy remapping techniques to correct them
US10529439B2 (en) 2017-10-24 2020-01-07 Spin Memory, Inc. On-the-fly bit failure detection and bit redundancy remapping techniques to correct for fixed bit defects
US10679685B2 (en) 2017-12-27 2020-06-09 Spin Memory, Inc. Shared bit line array architecture for magnetoresistive memory
US10395712B2 (en) 2017-12-28 2019-08-27 Spin Memory, Inc. Memory array with horizontal source line and sacrificial bitline per virtual source
US10395711B2 (en) 2017-12-28 2019-08-27 Spin Memory, Inc. Perpendicular source and bit lines for an MRAM array
US10360962B1 (en) 2017-12-28 2019-07-23 Spin Memory, Inc. Memory array with individually trimmable sense amplifiers
US10930332B2 (en) 2017-12-28 2021-02-23 Spin Memory, Inc. Memory array with individually trimmable sense amplifiers
US10891997B2 (en) 2017-12-28 2021-01-12 Spin Memory, Inc. Memory array with horizontal source line and a virtual source line
US10516094B2 (en) 2017-12-28 2019-12-24 Spin Memory, Inc. Process for creating dense pillars using multiple exposures for MRAM fabrication
US10424726B2 (en) 2017-12-28 2019-09-24 Spin Memory, Inc. Process for improving photoresist pillar adhesion during MRAM fabrication
US10811594B2 (en) 2017-12-28 2020-10-20 Spin Memory, Inc. Process for hard mask development for MRAM pillar formation using photolithography
US10360961B1 (en) 2017-12-29 2019-07-23 Spin Memory, Inc. AC current pre-charge write-assist in orthogonal STT-MRAM
US10424723B2 (en) 2017-12-29 2019-09-24 Spin Memory, Inc. Magnetic tunnel junction devices including an optimization layer
US10199083B1 (en) 2017-12-29 2019-02-05 Spin Transfer Technologies, Inc. Three-terminal MRAM with ac write-assist for low read disturb
US10236047B1 (en) 2017-12-29 2019-03-19 Spin Memory, Inc. Shared oscillator (STNO) for MRAM array write-assist in orthogonal STT-MRAM
US10236048B1 (en) 2017-12-29 2019-03-19 Spin Memory, Inc. AC current write-assist in orthogonal STT-MRAM
US10546624B2 (en) 2017-12-29 2020-01-28 Spin Memory, Inc. Multi-port random access memory
US10270027B1 (en) 2017-12-29 2019-04-23 Spin Memory, Inc. Self-generating AC current assist in orthogonal STT-MRAM
US10886330B2 (en) 2017-12-29 2021-01-05 Spin Memory, Inc. Memory device having overlapping magnetic tunnel junctions in compliance with a reference pitch
US10840439B2 (en) 2017-12-29 2020-11-17 Spin Memory, Inc. Magnetic tunnel junction (MTJ) fabrication methods and systems
US10840436B2 (en) 2017-12-29 2020-11-17 Spin Memory, Inc. Perpendicular magnetic anisotropy interface tunnel junction devices and methods of manufacture
US10784439B2 (en) 2017-12-29 2020-09-22 Spin Memory, Inc. Precessional spin current magnetic tunnel junction devices and methods of manufacture
US10367139B2 (en) 2017-12-29 2019-07-30 Spin Memory, Inc. Methods of manufacturing magnetic tunnel junction devices
US10255962B1 (en) 2017-12-30 2019-04-09 Spin Memory, Inc. Microwave write-assist in orthogonal STT-MRAM
US10339993B1 (en) 2017-12-30 2019-07-02 Spin Memory, Inc. Perpendicular magnetic tunnel junction device with skyrmionic assist layers for free layer switching
US10141499B1 (en) 2017-12-30 2018-11-27 Spin Transfer Technologies, Inc. Perpendicular magnetic tunnel junction device with offset precessional spin current layer
US10229724B1 (en) 2017-12-30 2019-03-12 Spin Memory, Inc. Microwave write-assist in series-interconnected orthogonal STT-MRAM devices
US10236439B1 (en) 2017-12-30 2019-03-19 Spin Memory, Inc. Switching and stability control for perpendicular magnetic tunnel junction device
US10319900B1 (en) 2017-12-30 2019-06-11 Spin Memory, Inc. Perpendicular magnetic tunnel junction device with precessional spin current layer having a modulated moment density
US10468588B2 (en) 2018-01-05 2019-11-05 Spin Memory, Inc. Perpendicular magnetic tunnel junction device with skyrmionic enhancement layers for the precessional spin current magnetic layer
US10438996B2 (en) 2018-01-08 2019-10-08 Spin Memory, Inc. Methods of fabricating magnetic tunnel junctions integrated with selectors
US10438995B2 (en) 2018-01-08 2019-10-08 Spin Memory, Inc. Devices including magnetic tunnel junctions integrated with selectors
US10388861B1 (en) 2018-03-08 2019-08-20 Spin Memory, Inc. Magnetic tunnel junction wafer adaptor used in magnetic annealing furnace and method of using the same
US10446744B2 (en) 2018-03-08 2019-10-15 Spin Memory, Inc. Magnetic tunnel junction wafer adaptor used in magnetic annealing furnace and method of using the same
US10784437B2 (en) 2018-03-23 2020-09-22 Spin Memory, Inc. Three-dimensional arrays with MTJ devices including a free magnetic trench layer and a planar reference magnetic layer
US10734573B2 (en) 2018-03-23 2020-08-04 Spin Memory, Inc. Three-dimensional arrays with magnetic tunnel junction devices including an annular discontinued free magnetic layer and a planar reference magnetic layer
US10529915B2 (en) 2018-03-23 2020-01-07 Spin Memory, Inc. Bit line structures for three-dimensional arrays with magnetic tunnel junction devices including an annular free magnetic layer and a planar reference magnetic layer
US11107978B2 (en) 2018-03-23 2021-08-31 Spin Memory, Inc. Methods of manufacturing three-dimensional arrays with MTJ devices including a free magnetic trench layer and a planar reference magnetic layer
US11107974B2 (en) 2018-03-23 2021-08-31 Spin Memory, Inc. Magnetic tunnel junction devices including a free magnetic trench layer and a planar reference magnetic layer
US10411185B1 (en) 2018-05-30 2019-09-10 Spin Memory, Inc. Process for creating a high density magnetic tunnel junction array test platform
US10615337B2 (en) 2018-05-30 2020-04-07 Spin Memory, Inc. Process for creating a high density magnetic tunnel junction array test platform
US10593396B2 (en) 2018-07-06 2020-03-17 Spin Memory, Inc. Multi-bit cell read-out techniques for MRAM cells with mixed pinned magnetization orientations
US10600478B2 (en) 2018-07-06 2020-03-24 Spin Memory, Inc. Multi-bit cell read-out techniques for MRAM cells with mixed pinned magnetization orientations
US10692569B2 (en) 2018-07-06 2020-06-23 Spin Memory, Inc. Read-out techniques for multi-bit cells
US10559338B2 (en) 2018-07-06 2020-02-11 Spin Memory, Inc. Multi-bit cell read-out techniques
US10650875B2 (en) 2018-08-21 2020-05-12 Spin Memory, Inc. System for a wide temperature range nonvolatile memory
US10699761B2 (en) 2018-09-18 2020-06-30 Spin Memory, Inc. Word line decoder memory architecture
US10971680B2 (en) 2018-10-01 2021-04-06 Spin Memory, Inc. Multi terminal device stack formation methods
US11621293B2 (en) 2018-10-01 2023-04-04 Integrated Silicon Solution, (Cayman) Inc. Multi terminal device stack systems and methods
US10580827B1 (en) 2018-11-16 2020-03-03 Spin Memory, Inc. Adjustable stabilizer/polarizer method for MRAM with enhanced stability and efficient switching
US11107979B2 (en) 2018-12-28 2021-08-31 Spin Memory, Inc. Patterned silicide structures and methods of manufacture

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